Episode 494: Robert Seacord on Avoiding Defects in C Programming : Software program Engineering Radio


Robert Seacord, writer of Efficient C, The CERT C Coding Commonplace, and Safe Coding in C and C++, discusses the highest 5 safety points and the instruments and strategies you’ll be able to make use of to write down safe code in C. Host Gavin Henry spoke with Seacord concerning the C requirements, strings, arrays of chars, null pointers, buffer overflows, reminiscence leaks, corrupt reminiscence, how this may be exploited, unhealthy inputs, dangling pointers, the stack, the heap, reminiscence allocators, knowledge constructions, enum surprises, C23, compilers, committee conferences, Annex Ok safe operate choices, static and dynamic evaluation instruments, good IDEs, fuzzing, gcc and clang choices, MISRA C, CERT C and ensuring you perceive C so you’ll be able to write C packages accurately to start with, slightly than counting on trial and error strategies.

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Gavin Henry 00:01:06 Welcome to Software program Engineering Radio. I’m your host, Gavin Henry, and immediately my visitor is Robert Seacord. Robert Seacord is a Technical Director at NCC Group the place he develops and delivers safe coding coaching in C and C++ and different languages. Seacord is an professional on the C Requirements. His six earlier books embrace CERT C Coding Commonplace and Safe Coding in C and C++. Robert, welcome to Software program Engineering Radio. Is there something I missed in your bio that you just’d like so as to add?

Robert Seacord 00:01:36 No, that was fairly full. Thanks for having me right here.

Gavin Henry 00:01:40 A pleasure. So, I’d like to start out off with a quick historical past of the C language after which contact on why programming in C could be insecure. We’re going to additionally then transfer on to high 5 safety points. After which the final little bit of the present goes to be speaking on the assorted methods and instruments we are able to use to assist us write safe C packages. Okay? Small disclosure, I would point out an open-source challenge I’m engaged on referred to as SentryPeer, which is written in C for numerous issues which have come up whereas I’ve been writing the code and instruments. I discovered safety points I believed that weren’t a difficulty and issues I discovered in your books and the sections on find out how to enhance your code. I feel it’ll be a pleasant bit. So, let’s lay down some foundations: when was C created?

Robert Seacord 00:02:35 I needed to look this up as a result of I’m truly not fairly that previous, however it first appeared in 1972. And it was developed by Dennis Ritchie at Bell Laboratories in New Jersey. So, it’s had a really lengthy historical past. It was primarily based on a typeless language referred to as B, as you may think, as a result of programmers have by no means been excellent at naming issues.

Gavin Henry 00:03:01 Cool, are there such a factor as variations, or how does that work?

Robert Seacord 00:03:05 Nicely yeah, there’s lots of variation in what we name C, proper? So, there was KRC, which was a Kerningham-Ritchie, sort of corresponded to their e book again within the 70s. And again within the 70s, ANSI began a committee to standardize the language. So that they revealed their first customary in 1989. In order that’s also known as C89, and the following yr that was revealed by ISO. So it was quick observe to the worldwide requirements group as C90, and lots of people have assured me, together with John Benito, who was the earlier convenor of the C requirements committee, that these two requirements are precisely the identical. There’s only a totally different cowl web page. However it’s truly fairly arduous to seek out copies of these unique requirements. However lots of embedded code continues to be written in C90 after which there’s been a number of variations, main variations of the Commonplace launch license.

Robert Seacord 00:04:10 So the following one was C99. And C99 was just a little sluggish on adoption, however it had a bunch of options. C11 was the primary customary that I labored on from starting to finish, and C11 primarily launched parallel programming, concurrent programming, threads, thread library, atomics. And it was meant to additionally handle safety. I’m undecided it did pretty much as good a job of addressing safety because it did addressing parallel execution, however we did add issues like Annex Ok, which is the certain checking interface or the underbar S features. Many individuals suppose that underbar S operate stands for Safety, however it truly stands for Bounds Managed Interface. And we added that we had an Annex L, which was analyzability annex and we made another small enhancements right here and there to deal with safety. That was C11. Yeah. 2011. We simply had the only digits I imply, I assume ultimately we’ll wrap round, however I hope to be useless by then and count on it to be another person’s downside.

Gavin Henry 00:05:31 You talked about ANSI, that’s the American…?

Robert Seacord 00:05:33 Yeah, that’s American Nationwide Requirements Institute however these days it’s truly, there’s a gaggle referred to as Insights, which is type of below the umbrella of ANSI. And so, in case you are within the US you’re a member of the Insights Committee, and Insights will get a single vote in ISO, so ISO is the Worldwide Requirements physique, so it’s one nation, one vote at ISO. And the Committee is definitely, it’s very US-centric. We had a gathering some years in the past in Delft within the Netherlands, and there’s a portion of the assembly the place, we simply deal with Insights enterprise. So we requested individuals who aren’t a part of the US physique to depart. And the one individual to depart was the host of the assembly. And this was a gathering going down in Europe. There was just one European there, and it was the host. So normally we get higher participation from Northern Europe, Canada, however not a lot past there; hasn’t been lots of participation from Asia or elsewhere recently.

Gavin Henry 00:06:50 And is that as a result of C’s not used there, or they don’t take part?

Robert Seacord 00:06:54 It is likely to be used there, however it’s all of the compiler distributors are within the US primarily. There’s IBM, their compiler group is in Markham in Canada. And so, that’s truly the Canadian illustration is from IBM, the well-known Canadian firm, in fact.

Gavin Henry 00:07:16 So there’s not likely variations; it’s the usual and that adjustments every…?

Robert Seacord 00:07:24 Yeah, so the variations of the usual, after which that type of drives the baseline. So there’s C11, C17. C17, some individuals mistakenly name it C18 as a result of it was revealed by ISO in 2018, however it’s truly the 2017 customary. And that was actually an uncommon one. It was simply actually bug fixes of C11. So, nobody actually needs to be utilizing C11. C11 is like C17 with bugs, and C17 is C11 with out bugs, however there’s, in fact all of the compiler distributors repair all of the bugs in C11. So that you gained’t see them anymore, no matter which customary you specify. And so C17 is a present model and we’re at the moment engaged on C23 and the deadline for papers to introduce new options has come and gone as of this previous, I feel it was as of November. And so, we all know what’s not going to be in C23 proper now, which is something we haven’t acquired a paper on and what’s going to be in it’s nonetheless up within the air as a result of now we have to, we’ll see if we are able to get consensus on the remaining proposals which can be in entrance of the committee.

Gavin Henry 00:08:40 And that’s what leads to the compiler, doesn’t it — the model or customary the compiler helps?

Robert Seacord 00:08:47 Nicely, it might, proper? So to begin with, after we create the usual and C there’s a powerful requirement for present implementations, proper? So, the C committee greater than most committees doesn’t wish to invent issues. We’d like to seek out issues which can be being utilized in apply that might profit from standardization as a result of that may enhance portability over numerous platforms, after which get it into the usual. And generally the committee will, I’ll use the time period “make enhancements” to present apply. They do wish to fiddle and that’s good and unhealthy. I imply, it’s good to perhaps make some enhancements, however on the similar time now it’s not simply precisely present in apply anymore, that you just made some adjustments to it. And a few issues like Annex Ok, the committee fiddled with {that a} bit and acquired to the purpose the place the prevailing implementation from Microsoft grew to become non-conforming to the usual, they usually weren’t actually up for altering it. And so, the usual — I’m looking for a distinct phrase than “customary” — it units a normal.

Gavin Henry 00:10:11 No, however you touched on a superb level in there that the usual is there to strengthen portability. I feel that’s what you’re attempting to get to.

Robert Seacord 00:10:19 Yeah. However all these compilers, they’re at all times, every implementation, proper? Every compiler implementation exists over a continuum, proper? So, you’ll have a compiler that has say, perhaps it’s absolutely applied to C99, however they’re working in direction of implementing all of the C11 or C17 options, proper? And so it’s someplace in-between. After which most compilers have compiler-specific extensions that you should use, proper? Which aren’t standardized. And so, so each implementation there’s lots of variation, every type of customary model is type of a distinct taste of the language. After which the precise compiler implementations they’ll fall into totally different areas by way of which requirements they implement and which extra options. So, there’s a constant type of moveable spine, however there’s a specific amount of variation sort of constructed on high of that.

Gavin Henry 00:11:30 Yeah. Simply referring to the bit the place you spoke about it’s actually C17 and never C18, in my open supply challenge that I discussed, after I was getting the continual integration duties arrange, to construct my challenge with the compiler flags I placed on, it was GCC customary C18, trigger I’m operating Fedora Linux newest from my desktop, like develop on, however the runners have been, this code was constructed on GitHub. Trigger you’ve been to twenty LTS they usually didn’t have that flagged help in these PCCs. I feel it was there. Or after I was testing on internet BSD and open BSD, they didn’t, they solely help C11. So even issues, not even that a few years previous, they haven’t caught up or it’s simply the model of compile that was launched with the working system. So, I perceive what you imply by relying on how the compilers have been applied and who’s rolled them out.

Robert Seacord 00:12:31 Yeah. And , Microsoft has at all times been an fascinating case as a result of they’ve at all times been type of comfy, partially supporting requirements. So supporting components of requirements they like, however ignoring components they don’t.

Gavin Henry 00:12:46 However then it’s not likely a normal, is it? You both do all of it, otherwise you don’t.

Robert Seacord 00:12:50 Yeah, that’s true. So for a very long time, they didn’t like all of the components of C99, they usually simply sort of took a go on these bits, however they’ve type of introduced a path the place they need to type of change into extra aligned with the C customary. They haven’t been sending anybody to the committee conferences, so it’s arduous to inform precisely what their future relationship with the language is. However compilers like Clang and GCC do an excellent job sort of maintaining with the most recent model of the requirements. And you will get some, even C23 sort of options supported in these compilers as effectively.

Gavin Henry 00:13:36 Wonderful. Nicely, I’m going to maneuver us onto the following part of the present, which was actually concerning the high 5 safety points that I’ve provide you with a little bit of analysis, and I would like you to appropriate me on them. So earlier than we dig into these 5, if we might spend a minute or two to grasp why a C program could be insecure after which we’ll dig into the 5 points I’ve listed?

Robert Seacord 00:14:02 Nicely, yeah so, in all programming languages are insecure they usually’re all general-purpose programming languages. So all of them can type of obtain the identical issues, proper? So that they have the identical, they’re all Turing full, they usually’ve acquired totally different abstractions, totally different idioms for programming in these languages. However, in the best way languages are damaged they are often fairly totally different, proper? As a result of that’s, that’s not an intentional design; it’s type of the defect floor of the language, or nevertheless you need to describe it. And so, if you happen to have a look at a language like Java, which had been billed as a safe language for a few years, it’s acquired some critical issues with issues like deserialization, which principally permits an attacker to execute their very own code inside your digital machine.

Gavin Henry 00:15:07 Very topical language for the time being, isn’t it with every part that’s been occurring the previous two weeks. We have now to watch out of timelines on any such present, however the huge with log4 J.

Robert Seacord 00:15:22 Yeah. And I imply, that’s, I haven’t studied that fastidiously. I imply, that largely looks like a design flaw.

Gavin Henry 00:15:29 It’s sort of, such as you stated, the place code could be injected and it runs the place it shouldn’t be.

Robert Seacord 00:15:34 So yeah Java has acquired a fairly vital assault floor and it’s at a sure stage the place it type of within the libraries and within the options and ways in which these options could be type of misused to use the code, C being type of a less complicated compiled language doesn’t have that assault floor. However C and C++ are type of well-known for reminiscence issues of safety. And these are issues the place, principally, you learn or write exterior the bounds of an object and C and C++, these languages are designed to be optimally environment friendly. So that they type of belief the programmer’s not going to make these kind of errors. And it seems that belief had been very misplaced as a result of programmers make these errors on a regular basis. And if you happen to write exterior the bounds of an object, that may have numerous penalties as undefined conduct, relying on what that write does it might overwrite knowledge, it might overwrite operate pointers, it might overwrite the return handle on the stack. And attackers can exploit that sort of downside by amongst different issues, injecting code into your course of and overwriting the return handle on stack with the handle of that malicious code so when a operate goes return, as a substitute of returned to the caller, it executes codes that’s been injected by the attacker after which that code runs with the permissions of the weak course of. In order that’s a fairly vital fashion of assault.

Gavin Henry 00:17:25 Okay. Nicely that’s a superb overview of some issues that will be insecure. Let me break down a few of them earlier than we begin on this subsequent bit, after we’re speaking about C you talked about the phrase object, which at all times makes me consider an object-oriented program, like a JavaScript object or a Java one, what will we imply in C after we discuss an object?

Robert Seacord 00:17:49 Oh, I didn’t know this was going to be a extremely deeply technical dialog.

Gavin Henry 00:17:54 Nicely, I suppose you may make it only a single-sentence definition of an object.

Robert Seacord 00:18:02 Yeah. We have now a reminiscence administration research group that’s attempting to reply that query.

Gavin Henry 00:18:07 Possibly we are able to’t do a easy reply then?

Robert Seacord 00:18:10 However principally an object is –- okay, I imply, in C you have got features and you’ve got objects, proper? So an object is every part that’s not a operate. In order that’s a, variable can be an object or you’ll be able to have an object in dynamically allotted storage. So yeah, it’s principally a…

Gavin Henry 00:18:31 Sure, that’s appropriate. That’s precisely what I used to be simply going to learn out of your e book. So in your e book, Efficient C, you say “an object is storage in which you’ll symbolize values. To be exact, an object is outlined by the C customary as a area of knowledge storage within the execution surroundings, the contents of which may symbolize values.” The added be aware “when a reference object could be interpreted as having a specific kind.” So yeah, that could be a huge tick for that reply. Thanks.

Robert Seacord 00:19:03 Thanks, I’m glad I’m constant.

Gavin Henry 00:19:06 So yeah, you touched on a few issues that I used to be going to tug aside shortly on that to do with how these reminiscence points are literally exploited. We’ll begin off from my checklist. So do my very own challenge and different issues like that at any time when I save one thing or I’m engaged on an ID and I push it to Github, I’ve acquired all types of static evaluation on it that we’ll point out it within the subsequent part, however it normally comes again with one thing like a string problem. So I’ve at all times understood strings to be a safety problem as in not terminated or an array of characters. Folks deal with it not as a string when it’s not a string. Might you give us some data on why a string could be insecure?

Robert Seacord 00:19:56 Yeah. Strings are sort of tough. So strings are, they’re not a primitive kind in both C or C++. So that they’re constructed on high of arrays and C arrays are problematic in and of themselves, proper? And so for starters, we all know that there’s no implicit bounds checking and there’s lots of features corresponding to stir copy the place you’re copying a string from a supply to a vacation spot, and it’s going to repeat your entire size of the string, however there’s no indication in that operate of the scale, say of the vacation spot array. And so stir copy will simply do what you ask it to do, which is copy from this sources, this vacation spot, with out checking to see if there’s room for that, to make that duplicate of string contained in the bounds of that vacation spot object.

Robert Seacord 00:21:00 And so the issue with the arrays, one of many issues with arrays is if you go them to a operate, they decay to a degree or two, the primary aspect of the array. And so when you’re contained in the operate, there is no such thing as a solution to decide the scale of your entire array. In order that measurement data needs to be handed to be obtainable. So features like stir copy that don’t handed the scale, there’s a library features, trusting you the programmer to go it an object, which can match to the vacation spot. Proper. And if it doesn’t, you’ll have this undefined conduct and this doubtlessly weak code.

Gavin Henry 00:21:45 I at all times do not forget that the identify of an array can also be a pointer. So if you go it right into a operate that, such as you stated, it, the keys to simply the pointer, you’ll be able to nonetheless discover out what kind of level that’s inside your operate? So is that appropriate?

Robert Seacord 00:22:05 Nicely, I imply, the kind of the purpose is the pointers tight so, I imply, you may have void pointers in C, however that’s not significantly a fantastic concept. So usually a string can be a char pointer, I imply, usually, I imply, accurately, it could be a char pointer. However you don’t know the way lengthy it’s. And even, the concept that it’s an array shouldn’t be essentially the case, proper? It might simply be a pointer to a single character.

Gavin Henry 00:22:41 So do you need to take into consideration what might I’ve seen the place they go within the lens? They normally lose one of many customary features, string lands, however once more, that operate has to determine how lengthy the string is. So do you need to take an additional step and ensure it’s not terminated? Or do you have got, or is there one thing that we are able to attain to so we don’t have to consider any of this for strings? What do you advocate?

Robert Seacord 00:23:08 So once more, there’s no string kind, there’s no premise string kind. So it’s an array and the definition of a string is that principally there’s no character earlier than the certain, proper? So if there is no such thing as a character earlier than the certain, it’s not truly a string, itís a personality array, proper? And that’s okay. It’s okay to have a personality array in C, it’s outlined conduct. However it turns into undefined conduct if you happen to go a personality array right into a stirling operate. As a result of it’s going to look at every aspect of that character array for no character. And it’s going to proceed searching for no character to seek out one. So if string size, which once more it doesn’t take a measurement, it doesn’t know what measurement the string is that it’s inspecting. If it doesn’t discover a no character earlier than the certain, it’s going to proceed to search for a match by reminiscence for no character. And as quickly as that operate, accesses storage past the bounds of the array, it’s now undefined conduct, proper? And upon getting undefined conduct in your code, all bets are off. That program can now exhibit any kind of conduct. So there’s actually requirement to make sure that any string you go to a string operate is definitely a string, which means that it has no termination earlier than the certain.

Gavin Henry 00:24:41 Yeah. I’ve seen a number of the documentation on a number of the string features that look to work across the area. Then they are saying, if there’s no unknown character discovered at that size that you just go, then we’ll ensure that there’s one there.

Robert Seacord 00:24:58 Proper, and lots of features, newer type of safer features will make sure that once they create a string, that it’ll, it is going to be correctly, no terminated. If you happen to, if you happen to maybe give it extra knowledge than it has room to retailer in no matter sized object you have got, then it’ll overwrite the final character attempting to retailer with a no character. So that you’ve acquired a correctly, no terminate string. And so I imply this selection of a datatype was made early on and will very effectively be the incorrect knowledge kind. I imply perhaps having a measurement adopted by the string and never utilizing a no termination, perhaps that will have been a greater extra environment friendly, safer design, however it’s not one thing that’s prone to change at this level within the, within the evolution of those languages.

Gavin Henry 00:26:02 And I feel to maneuver on to quantity two on my checklist now, I feel we’ve touched just a little bit on it and I’ve referred to as this buffer overruns and underruns, and I feel you’ve helped me perceive the query I used to be going to ask within the part the place in my challenge, basically, Peer one, I’ve acquired some errors on my ID the place I’m doing a, I feel it’s a string and evaluate some, principally checking a URL that is available in to see if it matches the info to one among my features. So I’ve acquired the URL and I’ve acquired how the scale of how lengthy it went to look alongside the array of chart to discover a match principally. So I’ve given it a max paths size, I feel it’s of 1,024 or one thing. However my ID says, I shouldn’t verify that URL string longer than the strings there, though it finds a match. So my duties all work, as a result of I feel that’s simply what you’ve defined there. As soon as it will get previous the chart of the array of chart, which could not be a string I exploit not terminated, all bets are off as a result of it’s on the positive conduct when it will get to say chart 101 of the URL, that’s 100 chart lengthy.

Robert Seacord 00:27:21 You undoubtedly can’t study characters past the bounds of that object, past the bounds of that character array.

Gavin Henry 00:27:31 Sure so I feel when the URL is available in, it’s essential to do a measurement verify on it after which ensure you’re not checking previous that from match, is that the proper method?

Robert Seacord 00:27:40 Sure. I imply, so that you’ve acquired a max path buffer that you just’re storing it in. So that you’ve acquired that quantity of room for that array, however you’re evaluating it to a different string. And so that you don’t need to exceed the bounds of both of these character array.

Gavin Henry 00:28:04 Really the string and evaluate. So I’ve acquired the URL on the size of the string that I need to evaluate towards. So like 4 slash house, I need to be sure that goes to the fitting place or about, or one thing about web page and I’ve acquired a max size. So it’s going alongside that string for so long as I handed size for when it says thatís unhealthy, however you don’t know the way lengthy the trail is till you’ve calculated the trail. We sort of get on this rooster and egg kind state of affairs. However yeah. So after we discuss going previous the top of array, that will be an overrun? Is {that a} buffer overrun? Or is that an underrun?

Robert Seacord 00:28:46 So there’s these phrases that they kicked round in safety like buffer overflow and buffer underrun and overrun. And I don’t know what any of these phrases imply. I imply they’re sort of loosely used phrases in safety, however they don’t have very exact definitions. So within the C language, actually, we simply discuss an entry exterior of the bounds of an object. And we don’t care about what that entry appears like, proper? So you may begin in the beginning of an array and you may increment a degree or an index after which run off the top of the array, proper? And that’s an out of certain entry. You may name {that a} buffer overflow. After which you may begin on the finish of an array and you may detriment the pointer and you may run off that finish of the reminiscence.

Robert Seacord 00:29:42 Typically you’ll simply type of arbitrarily soar from, you may need some type of integer right here and soar from accessing an array to some random place and reminiscence. And once more, I don’t know what that’s referred to as. That’s a buffer overflow or buffer overrun, however it’s simply, it’s undoubtedly an entry exterior of the bounds of that object, which is undefined conduct. You possibly can’t take a degree or two in an array and you may add or subtract interger worth to it. So long as the pointers nonetheless refers back to the similar array or to 1 path that array the too far aspect. But when the pointer you type from that pointer arithmetic, is exterior of that certain, it’s simply undefined conduct. And what you name it, sort of varies. There’s it’s just a little bit unrelated, however individuals like to speak about integer overflow and integer underflow in C, however there’s truly no such factor as integer underflow. That’s simply somebody’s creation. You probably have an operation into operation at types of worth, that may’t be represented, that’s integer overflow there’s there is no such thing as a such factor as integer underflow, however individuals like to make use of that time period for no matter cause.

Gavin Henry 00:31:07 Nicely, it’s a superb rationalization. Thanks. So we’ve performed one thing right here the place we’ve gone exterior the bounds of what we’re attempting to do. The third factor on my checklist is what I’ve referred to as reminiscence leaks. So if you request some reminiscence from the working system with one of many allocation features and also you don’t free it, so that you get what I feel is known as the incorrect time leak, runtime leak or corrupt reminiscence. So runtime can be the place you’re regularly asking for this reminiscence, however you’re not releasing it. So that you’re utilizing greater than try to be. Is {that a} appropriate definition?

Robert Seacord 00:31:47 Thereís lots of stuff that was barely incorrect in that query.

Gavin Henry 00:31:53 Thatís what I need to hear. Right me.

Robert Seacord 00:31:55 Yeah. So for starters there’s a reminiscence allocation operate, proper? Malik Cadillac, realigned Alec, and none of those instantly request reminiscence from the working system. Proper? So the method has a reminiscence allocator that runs as a part of the identical course of base, proper? And so your reminiscence allocator will request a really giant block of reminiscence from the working system, after which it’ll handle that. And so if you make a name to Malik, it’s allocating storage, is allocating a bit of storage from this huge block of reminiscence that the reminiscence managerís managing inside the course of, proper?

Gavin Henry 00:32:38 So a part of the kernel that’s doing this reminiscence administration?

Robert Seacord 00:32:42 No, it’s all in your course of. So the reminiscence administration, you’re going to hyperlink to a library and that library has implementations of stir copy and Malik, and all of those features run as a part of your executable, in your course of.

Gavin Henry 00:32:58 So this isn’t like a reminiscence pool that I’ve created. That is one thing to do with how I execute invoice has created?

Robert Seacord 00:33:05 So I imply, if you begin up, the reminiscence supervisor goes to go to the working system, itís going to get a block of reminiscence. However then as soon as it will get this huge block, which is principally the heap, your reminiscence supervisor shouldn’t be going to handle that heap storage for you. So, if you make a request to Malik, that’s going to execute the Malik operate, which is a part of this reminiscence supervisor implementation. And it’s going to say what’s the following obtainable variety of the following obtainable block of reminiscence that’s at the least this variety of bytes giant, and carve that off this greater block and return that to the person. In order that total course of doesn’t contain the Kernel at that time, proper? That blocks thatís been carved out. The one time they’ll Kernel may change into concerned once more is if you happen to utterly use all of the allotted reminiscence from the working system, you may then search to type of lengthen that. However that one implementation doesn’t essentially, I imply, the opposite chance is that at that time, that location would fail for an insufficient reminiscence.

Gavin Henry 00:34:23 Okay and so after we’re speaking about these bounce issues that occur, I’m not going to make use of the phrase overrun or undrawn okay. Does it make a distinction if it’s over, does one thing I’ll bounce into reminiscence that we haven’t freed, or are we contained inside what the reminiscence allocation instrument has given us from reminiscence? Or is it simply undefined? Is there a distinction between, so we’ve corrupt a few of our personal reminiscence aren’t free to, after which one among these array operations we’re doing finally ends up attempting to enter that it’s simply undefined or? What Iím attempting to ask is, if you see exploits of these kind of issues, and there, they know that we’re not cleansing up reminiscence, or there’s some kind of reminiscence they will get to with this exploit to run their very own code. How do they predictably get out that if these items have been all fairly undefined and random?

Robert Seacord 00:35:23 Nicely, an undefined is a time period utilized by the usual, proper? So, the usual says, merely we haven’t outlined what occurs right here. And so specific implementation is in fact, goes to do one thing. And since it’s not outlined by the usual, what it does, you as a programmer don’t actually know what it does, proper? So generally the implementation type of align along with your expectations of program or what kind of conduct you’re going to get, by which case you may have code, you may have executable generated from code containing undefined conduct, which is definitely appropriate, however extra generally if you happen to’re invoking undefined conduct that implies that you just don’t have an accurate understanding of the language, almost about that conduct. And most probably the code is ISRA. Now after we discuss reminiscence, warmth reminiscence, there’s a number of courses of potential errors, which may result in vulnerabilities. The primary one, which we’ve sort of mentioned in arrays, buffer overflows, proper?

Robert Seacord 00:36:38 So buffer, overflows can happen in any reminiscence section to allow them to happen within the stack, within the knowledge section or within the heap. And the consequence is, so an overflow within the heap, and anytime you write exterior the bounds of an object, itís undefined conduct.

Gavin Henry 00:36:57 Are you able to outline the stack within the heap briefly simply in context?

Robert Seacord 00:37:01 So the stack within the heap, I imply Iíll say, Iíll begin out by saying that neither idea is outlined within the C customary. So these are sort of like implementation ideas, however usually a stack is an information construction which helps program execution by permitting you to have a operate that calls one other operate after which creates a stack body for operate that it’s calling the place it preserves all of the native variables and arguments which can be being handed to that operate and so forth.

Robert Seacord 00:37:42 After which that operate might name one other operate and that operate might recurse, proper? So you may wind up with a number of cases of the identical operate on the stack. After which as soon as the operate returns, the stack type of unwind. So you’ll flip again to the calling operate and re-established that operate stack body so it has entry to the native variables. And so the execution stack is an information construction to permit for this principally purposeful fashion of programming. In order that’s a stack and typical variable that you’d declare inside a operate, a non-static variable, if you happen to simply have a operate app and also you IDE, that variable an automated variable, that’s declared within the scope of that operate. And what occurs is if you name that operate, a stack body will get created for that operate and cases that variable will get allotted on the stack, proper?

Robert Seacord 00:38:44 And so as soon as that operate returns the lifetime of that, that variable ends, and it may well not be accessed. So that you’ve acquired two different knowledge segments. You’ve the info section, which is the place static variables go and static variables, will the place variable are, they’ve the identical lifetime as that of this system. So that they’re at all times accessible. And that’s the place you may maintain a counter or one thing, proper? The place operate will come, you’ll name a operate node, you’ll increment this counter, the operate will exit, however the rely will nonetheless stay as a result of it’s a world variable. And international variables have their makes use of they usually have their issues. However the subsequent kind of the following section is the heap. And the heap is the place dynamically allocate storage exist. And the heap lets you allocate storage as you want it throughout program execution.

Robert Seacord 00:39:52 And people objects persist till they’re explicitly de-allocated or destroyed. So, these have their very own sort of lifetime. It’s primarily based on you, allocating and de-allocating.

Gavin Henry 00:40:08 In order that’s the place the leak might occur. Corrupt.

Robert Seacord 00:39:12 Yeah. So there’s the buffer overflows on the heap, and people are exploitable and the way they’re exploited depends upon the implementation of your reminiscence supervisor. Some reminiscence managers implement the knuth algorithm, which makes use of every boundary tags the place you’ll have management constructions earlier than and after every allotted blocks. So if you happen to write past the bounds of the allotted object, you’ll begin overriding these management constructions within the heap, corrupting the heap, and an attacker might overwrite these constructions principally once more, to our safety per informed. And the specifics of that rely on the implementation of the allocator.

Robert Seacord 00:40:58 However there’s additionally two different courses of issues, at the least two different class issues with reminiscence, allotted reminiscence. So, one is you allocate reminiscence, and you then fail to deallocate to launch it. That’s a reminiscence leak. And a reminiscence leak could be benign if in case you have a brief operating program and also you don’t ever exhaust reminiscence. However if in case you have one thing like a server that’s going to run for prolonged durations of time, because it runs, if it’s persevering with leaking reminiscence, that reminiscence is not obtainable to the reminiscence allocator to allocate to the method. So ultimately that system goes to exhaust reminiscence and that kind of defect as soon as that occurs, your server’s not going to be very efficient at serving. As a result of it’s going to start out having reminiscence failures and continuously be in a state of attempting to get well from reminiscence errors.

Robert Seacord 00:42:05 And in order that state of affairs is type of often called useful resource exhaustion. And one type of assault is denial of service assault by useful resource exhaustion, proper? The place an attacker finds a reminiscence leak in your system, exploits that to exhaust your reminiscence. And now it seems that your server is operational, however truly it’s not serving requests as a result of it’s out of reminiscence and it may well’t operate correctly. So out of reminiscence, failing to correctly deallocate storage when it’s not required, can result in these types of denial of service assaults. The opposite downside is you’ll be able to unintentionally launch the identical storage a number of instances. And that’s also known as double free vulnerability. Double free vulnerability is, it appears just a little bit totally different, however it may well have the identical consequence as a buffer from the heap, which is that an attacker might exploit that to execute arbitrary code. So double free can also be fairly harmful type of coding error.

Gavin Henry 00:43:17 Would you be capable of give an instance of, I do know it’s arduous as a result of it depends upon this system on implementation of the place it’s operating and issues, so far as I perceive it. However how can an attacker exploit what you simply defined with a double free, or an over or below on how did they get this code. Is it assembling language that they put within the code they usually inject that into this reminiscence of space, space of reminiscence? Or what does that seem like?

Robert Seacord 00:43:45 So if we simply mentioned simply type of a fundamental exploit

Gavin Henry 00:43:53 Put in your identify or one thing, I donít know, one thing actually.

Robert Seacord 00:43:57 Yeah. In impartial of the error, what can occur is an attacker can inject executable directions into your course of reminiscence, and it may well actually try this on any enter operation and there’s legitimate, there’s executable codes, it appears like legitimate ASCII. Executable codes that appears like legitimate UTF strings. So no matter kind of string you’re inputting, it’s at all times a good suggestion to validate that string to the extent doable, however generally you simply can’t, generally it’s simply sort of a string knowledge.

Gavin Henry 00:44:38 That factor you actually acquired a superb part in your Efficient C e book on validating this system arguments on the commodity. I discover it actually intensive.

Robert Seacord 00:44:48 Oh, thanks. And I imply, safe coning and C and C++ actually goes into these exploits extra. The Efficient C e book is supposed extra of an introductory textual content it. So I don’t attempt to go too in depth in how exploits or find out how to write exploits. However I attempt to write that e book to offer sort of a powerful basis to programmer.

Gavin Henry 00:45:15 I feel that’s why I prefer it a lot.

Robert Seacord 00:45:18 Thanks. I imply, in a method if you happen to code accurately and also you keep away from undefined behaviors, your code is safe. You don’t want to grasp the way it is likely to be exploited, however the research of type of how code is exploited is actually motivational. It’s for individuals like, oh I’ve acquired legacy code base with tens of hundreds of errors. So how do I prioritize that? And so that you sort of discuss what the assorted errors are, how they are often exploited, the way you may mitigate towards these issues with generally type of runtime methods, which might defend towards exploits of all of those. After which additionally about safe coding practices, find out how to accurately code. So it was not exploitable. However getting a legacy system poorly written, legacy system to be safe is usually a vital funding in rewriting and bettering the code.

Gavin Henry 00:46:23 Yeah. I feel you’ve touched properly on to quantity 4, which is on my checklist, which has inputs. So I’ve acquired some inquiries to do with processing command line arguments, environmental variables, defensive programming, how community site visitors is processed about runtime into knowledge constructions, issues like that. I feel simply actually understanding, listening to what you defined with them, the reminiscence leaks and assault vectors. It simply depends upon how the enter is coming into your program and also you processed it accurately. That could possibly be the, the way it’s if you see the CVE exploit much less, and it says, there’s a double free or a buffer earlier than or one thing in sure conditions doing this, if the wind’s blowing Northwest and also you’re carrying your favourite jumper, this may get exploited kind factor. It simply depends upon the way it’s coming into that program and what this system does. Is {that a} honest abstract?

Robert Seacord 00:47:24 Yeah. A few of it’s fairly tough, proper? I imply, so that you’ll have a look at some supply code and it’ll have some undefined conduct and it is likely to be on this platform, below these circumstances with no matter runtime protections can be found. This specific coding error gained’t be exploitable, proper? However you may run that on. You would port that to a distinct system. You would run on a distinct platform, you may change one thing concerning the runtime surroundings, or you may improve your compiler the place the compilers now used to do one factor with an undefined conduct, however now it’s now they’ve developed an optimization that takes benefit of that undefined conduct to enhance your efficiency. And now an issue which was the error was at all times current within the supply code, however now due to this new optimization, that executable has been modified.

Robert Seacord 00:48:28 And it’s now weak to assaults. So generally, many instances it’s simpler to restore the code than it’s to grasp all of the potential safety penalties of an exploit. So some circumstances the place it’s low cost to repair, normally simply make sense to repair it. I imply, there’s some circumstances the place if you happen to put some code on the Mars Rover and also you landed on Mars, proper? It’s a bit extra concerned to restore that code, proper? So that you need to analyze that defect extra. You need to analyze that vulnerability extra to seek out out whether or not it’s how a lot it was safety danger is, is it price repairing or not, however many circumstances it’s simply simpler to you to make the restore to the supply code as a result of that’s the top outlined behaviors get rid of it, you shouldn’t have vulnerabilities usually. Now there are vulnerabilities which may exist absent of undefined conduct. These could be logical errors or simply easy issues like a reminiscence leak, proper? So in case your program unintentionally prints out or logs some personally identifiable data, it doesn’t essentially need to have undefined conduct to try this. Proper? So you may have, I virtually need to use the phrase insecure by design the place there’s not,

Gavin Henry 00:50:05 This has nothing to do with C, that’s simply engineering software program, engineering shouldn’t be proper?

Robert Seacord 00:50:10 Proper.

Gavin Henry 00:50:12 Okay. And I feel that was a superb abstract. And so with an improved compiler, might that cart to double free, if it’s monitoring the quantity of instances you freed one thing or what? A rubbish assortment system?

Robert Seacord 00:50:28 Oh yeah. Nicely, C doesn’t actually have rubbish assortment.

Gavin Henry 00:50:33 That was simply an instance.

Robert Seacord 00:50:34 Yeah. So double free, these kind of errors, there are methods to catch it. Proper? So, one mechanism is simply to, so compiler does some evaluation, proper? It doesn’t do lots of evaluation. So there’s, they’re static evaluation instruments that do extra depth, extra in-depth evaluation.

Gavin Henry 00:50:56 So I’m going to the touch on within the subsequent part, I’ve actually loved this center part. So again transfer us on as a result of we’re over our time on this. However so simply the very last thing I’ve in my checklist, as a result of I feel we’ve performed a extremely good job. And I didn’t say on the time, however I actually loved their description of the inventory and the heap that made every part actually clear. So the final level is, sorry, that was a foul pun. It’s dangling pointers. The place are these in what issues that they brought about only a minute or two, after which we’ll transfer on to the instruments that will help you be a greater programmer.

Robert Seacord 00:51:30 Nicely it actually brought about unhealthy puns, however the issue with a dangling pointer is that it could lead on sort of instantly to 2 courses of exploitable defects, proper? One being double free, which we’ve simply mentioned, proper? So if you happen to free a pointer and also you don’t assign it to know, you may free that pointer a your second time and we’ve already mentioned that may be weak. If you happen to do set it to know, and also you free a no pointer, that’s a no ops. In order that has no, no impact on the code. The opposite downside with that dangling pointer is that it’s now pointing to reminiscence, which has been deallocated presumably deallocate it after which reallocate it. So writing to that time, or is now undefined conduct and say for that storage is deallocated you write to it, when you deallocate storage, the reminiscence supervisor takes it over and it would use the sort of person area to insert management constructions to be able to observe, maintain observe of free blocks of storage. So if you happen to write to those dangling pointers, once more, you may overwrite these management constructions, corrupting the heap, and doubtlessly doing that in a method, which once more, makes it doable to execute arbitrary code.

Gavin Henry 00:52:50 Yeah. I’ve seen that in quite a bit in one thing that I do and in my code and in Guisetís e book who I had on the present and who since you work with them and Requirements, Episode 414, and in addition a shout out to your artwork’s name for the IEEE safe coding and C and C++, and strings and integers and your different article on Efficient C. How I’ve acquired these hyperlinks within the present notes, however all his, and I feel in your code examples, after free, the pointer is ready to zero, which is the null. Wonderful, that was a extremely good protection. Within the final part, I don’t have as a lot time as I hoped, however we’ve performed a superb in some crossovers right here. So we’ve acquired IDs and issues that we use as we’re operating the code that try to give us as a lot assist as doable. We’ve acquired a type of constructed instruments, however you talked about earlier static and dynamic evaluation. I feel you talked about dynamic evaluation however Iíll talked about it in right here anyway. So what static within the now and dynamic evaluation and the way do they assist?

Robert Seacord 00:54:00 These are simply sort of instruments and approaches to research the code and perceive what it does and what potential defects it may need.

Gavin Henry 00:54:14 So I appears on the supply code, the bodily recordsdata. Nicely, not bodily, the tax file.

Robert Seacord 00:54:19 So static code evaluation, it appears like a bit a compiler, proper? So it builds your supply code and construct usually in summary syntax tree. So it creates a construction after which it would construct some extra graphs that may be analyzed. And you then’ll have a collection of guidelines the place you say I don’t need to free a pointer after which free a pointer a second time. And so the static evaluation will study the graphs of the supply code, the summary syntax tree. And it’ll search for totally different structural, very structural defects within the code, or doubtlessly do some path evaluation or some knowledge movement evaluation. So static evaluation tends to be excellent at discovering, say structural issues in a program it’s not pretty much as good at knowledge movement and management movement kind.

Gavin Henry 00:55:19 There are issues which have caught me on that is the place you returned from the operate as a result of that is an error, however you haven’t freed what youíve allotted beforehand. That’s at all times one thing that I discover in my stuff.

Robert Seacord 00:55:34 There’s some issues which can be pretty amenable to a stack evaluation, however ceaselessly reminiscence administration concurrency, these aren’t at all times discoverable by stack evaluation. So typically dynamic evaluation is more practical to seek out these kind of issues. And so that you do have issues like handle sanitizer and thread sanitizer that obtainable in claying and GCC and, and these allow you to and a wide range of different merchandise, however these mean you can instrument the executable. After which as soon as it’s instrument that you just’ll train it, utilizing no matter number of checks you have got obtainable, maybe utilizing fuzz, fuzzers to drive the code with numerous inputs. And these interment executable is now we’ll be capable of principally entice on any type of violation. So their very dynamic evaluation is more practical at discovering issues just like the NAMIC reminiscence points and concurrency points, principally at run time.

Gavin Henry 00:56:52 A number of the issues that you just’ve talked about in your e book that I’ve performed with and I utilized in my initiatives is the sanitizer ones. The Tsan, which is the thread one, Asan which you talked about as effectively. The handle sanitizer for reminiscence issues, after which the Ubsan, which is the undefined conduct the place I appear to seek out errors utilizing these is after I’m operating my check suite, as a result of I’m not as cautious as I’m truly operating the core product because it have been. I at all times discover points the place I’ve set the duty case by I haven’t torn it down or one thing . Which is sort of a biggie and you must kind out as you discover them. After which a number of the different instruments I see different individuals use because the sanitizers, the clang sanitizer one that you just talked about, after which there’s a great deal of, I feel quite a bit, you talked about just a few in your e book, however if you happen to’ve acquired an open supply challenge, it’s fairly simple to get entry to all these free instruments. However I feel most of them are industrial. Iíll put the hyperlinks into my present notes for that.

Robert Seacord 00:57:56 And I don’t know the place to go along with this. I imply it actually, C is tough language.

Gavin Henry 00:58:05 It’s easy, however it’s merely arduous as effectively. Isn’t it?

Robert Seacord 00:58:10 Easy. I’m undecided. It’s smaller than different languages. And so I assume from that respect, you may say it’s easy, however thereís so many layers to it that I’m nonetheless peeling after I began programming C in ë95. So it was nonetheless peeling after.

Gavin Henry 00:58:33 And what kind of issues have you ever provide you with releasing just lately that stunned you?

Robert Seacord 00:58:38 So right here’s a superb one. This was in all probability the latest factor that stunned me. So you’ll be able to outline an Enum and you may have an enumeration fixed, which has a sort, which is totally different from the bottom kind of the enumeration kind.

Gavin Henry 00:58:57 Arenít Enum simply imagined to be a factor that meant one thing to you?

Robert Seacord 00:59:04 Nicely, there’s this query. There’s at all times this query of what’s the kind of these items, proper? So that you write enum colour, crimson, inexperienced, blue. Okay. So what kind are these issues?

Robert Seacord 00:59:12 So there’s a powerful tendency to, effectively, the usual will say that the numeration constants the crimson, inexperienced, blue, these ought to all be INT, however you may say, for instance, you may go your GCC to consumer, flag, which says use you brief enumeration content material. So in a case like that, crimson, inexperienced, blue GCC, your declare may say, oh I’ve solely acquired three values, 0 1 2. I can simply match that non signed char. So I’m going to save lots of various storage and make this time signed char. So now you’ve acquired the bottom kind of this object is unsigned char, however the kind of every enumeration fixed is INT. And largely you don’t discover this, however there are circumstances the place say you’re doing generic programming and also you’re attempting to execute some specific code primarily based on the kind of one thing. It’d come as a shock to individuals to find that the kind of the fixed is totally different than the kind of the enum object. That’s considerably shocking. That’s the one which’s acquired me most just lately.

Gavin Henry 01:00:36 You talked about one thing there that what’s the purpose of a signed char and an unsigned char. simply trigger you talked about it?

Robert Seacord 01:00:43 Nicely, signed char and unsigned char principally small integer varieties. If you wish to symbolize a personality, you must use char plain char and all three of these varieties are totally different and incompatible varieties.

Gavin Henry 01:01:00 Good. Okay. Simply earlier than we begin wrapping up the present, simply to place some extra meat into the instrument part, a superb cowl of static and dynamic evaluation. We’ve talked about the Tsan and Asan and Ubsan.

Gavin Henry 01:01:18 However over the present we spoke about Annex Ok, is that one thing that we are able to truly use immediately? Itís been out for some time. You talked about that in your e book and Jens talked about it in his. Do you advocate it?

Robert Seacord 01:01:34 Yeah. I prefer it. There are two faculty of ideas there and we voted on this within the committee a few instances and the neighborhood is equally divided on this half. The neighborhood hates it, half the neighborhood likes it. And since it’s in the usual, you’ll be able to’t get rid of it. You possibly can’t change the usual with out consensus, proper. It’s the established order, until you’ll be able to’t add something, you’ll be able to’t take away something with out consensus. And a number of the historical past of this, it began with Microsoft again within the 90ís as a response to some well-publicized vulnerabilities. And principally it type of improves upon the prevailing string library features by usually including an extra argument, which specifies the scale of vacation spot array. So now if you name these features, they will decide that there’s not sufficient room on this vacation spot array to make a replica of this string.

Robert Seacord 01:02:40 And so slightly than write past the bounds of the thing, I’m simply going to point an error both by invoking a runtime constraint handler or returning an error worth. And so I like these, I feel they enhance, they made it simpler for novice programmers to keep away from buffer overflows and undefined behaviors. Corporations like Cisco have used these extensively and swear by them. They declare to have had vital enchancment in high quality and safety is a results of utilizing these features. So they’re obtainable claying and GCC. A variety of the distributors type of don’t like these libraries that is likely to be as a result of they originated from Microsoft or could possibly be different causes, however there are third social gathering model of those libraries that you could obtain and use and they’re customary API. So I like them. I might advocate their use.

Gavin Henry 01:03:52 To complete off this part there’s requirements that we discuss. There’s the CERT C tips, proper. I keep in mind listening to point out by SQL Lite, how they spend a yr getting their C code as much as some medical requirements. Can’t keep in mind what it was. Is {that a} factor? Is that’s one thing youíve heard of? Some kind of medical requirements the place that code is appropriate to be deployed and medical gear, I’ve to do some extra seek for that. Okay, so I feel that was actually good to start out wrapping up. So clearly C is a really highly effective language with a powerful historical past and deployment base. But when there was one factor a software program engineer ought to keep in mind from our present, what would you want that to be? If we haven’t coated that or simply one thing you wished to deliver to the highest?

Robert Seacord 01:04:43 Okay, I’ll say this, we didn’t spend lots of time speaking about IDs, proper? However there’s an fascinating factor individuals say about C programmers is that C programmers are just a little pissed off by type of compiler diagnostics they usually need to get previous that to allow them to get to the true job of debugging this system, proper? And there’s one fashion of programming, which is that this trial and error, proper? So you have got a little bit of an issue. You Google, you go to stack overflow, you discover a code instance, you copy paste that into your system and also you tweak it. You compile it. It doesn’t compile there’s some diagnostics. Oh yeah. Ms. Title is variable misspells. It makes you enhancements that compiles and you then run it in, it doesn’t fairly run.

Robert Seacord 01:05:49 So you alter one thing and now you get a run that succeeds and also you’re like, cool, that’s working onto the following factor. And so this sort of strategy of trial and error, it may well get to a program which, which works in a sort of, optimum situation, proper? However it doesn’t imply that packages. Right, proper? You don’t know the way that program’s going to take care of sort of surprising knowledge. And we talked concerning the enter validation briefly, however actually your code has to work with all doable knowledge values, proper? There can’t be any inputs for which this system’s going to exhibit incorrect conduct. In order that’s the purpose of enter validation and programming normally, proper? Just remember to take care of all, all doable mixtures of knowledge. So to do that trial and error is actually inadequate. You want to perceive the language, it’s essential to perceive the code you’re writing and ensure you perceive all doable circumstances that you just’re contemplating kind conversions. You’re contemplating integer overflow and all these.

Gavin Henry 01:07:14 I switched to on Mesa, simply use tax, or I feel wherever you utilize and there’s a great deal of C plugins, and the period of time you save by simply taking a look at what will get highlighted or earlier than you even clicked construct, otherwise you’ve run a command. Most of your issues are solved if you happen to simply take note of the,

Robert Seacord 01:07:35 Yeah, it helps quite a bit, however it’s nonetheless undoubtedly insufficient as a result of all of the tooling, isn’t going to seek out all the issues. So it’s useful to grasp the language you’re utilizing. And you may obtain that by coaching courses. You possibly can obtain that by studying. One factor I did after I type of transitioned from being a programmer to a safe coder is I spent a while, largely in visible studio and I might, I’d write just a little little bit of C supply code and I might type of predict in my head what kind of meeting can be generated from that code. After which I might compile it after which I might be stunned. I might return and skim the usual, like, okay, now I perceive. And so, ultimately I acquired to the purpose the place I might efficiently predict the meeting code that’s being generated. Till you get to that time, your understanding of the language is type of falling brief, proper?

Gavin Henry 01:08:41 Yeah, there’s one thing to be stated for simply truly experimenting and I wish to name it “proving it to your self,” principally have the idea and write a activity or one thing.

Robert Seacord 01:08:55 Yeah. And what I do is ideal some code proper. The place I gained lots of confidence. I perceive this, I do know what that is. I can use this and now I’ve acquired a sort of a reusable part I can use, however it’s fairly harmful to type of simply throw in a bunch of issues as a result of they’re there with out actually understanding but. So, I imply, perhaps it’s extra enjoyable, however it doesn’t essentially produce safe programs.

Gavin Henry 01:09:28 So, simply to summarize earlier than we shut up the podcast, what one factor would you want them to recollect? Is that, be good along with your IDE, choose a superb one, or show your assumptions, or what would you want them to recollect out of that?

Robert Seacord 01:09:48 I might say the very best time to keep away from the defect is if you’re coding. It’s higher to write down appropriate code initially than it’s to attempt to discover and restore defects downstream. I imply, appropriate coding, high quality code, safe code, it’s tough to attain. And you really want to make use of all of the obtainable instruments and processes and self-discipline to get near attaining that. However yeah, a very powerful factor is type of writing code securely to start with.

Gavin Henry 01:10:39 Thanks. If individuals need to discover out extra and discover a few of these issues we’ve chatted about, the place’s the very best place to get in contact? You’re fairly lively on Twitter, is that the very best place?

Robert Seacord 01:10:49 Nicely, I could be discovered on Twitter. I’ve a web site, RobertSeacord.com, I feel the place I’ve acquired some errata for the Efficient C e book.

Gavin Henry 01:11:04 I feel it’s essential to replace your SSL certificates as I used to be taking a look at it final week and it was complaining that it was insecure of all issues. Okay. So your Twitter account and your web site.

Robert Seacord 01:11:16 You possibly can look there. I’m on LinkedIn, as effectively. I’m not very arduous to seek out, I don’t have any handles anyplace.

Gavin Henry 01:11:25 I assume it’s @RCS on Twitter for those who need to go there immediately. Okay. Robert, thanks for approaching the present. It’s been an actual pleasure. That is Gavin Henry for Software program Engineering Radio. Thanks for listening. [End of Audio]


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