[cfe-commits] r161440 - in /cfe/trunk: include/clang/Basic/DiagnosticSemaKinds.td test/Analysis/cstring-syntax.c

[Matt Beaumont-Gay]

Should we have similar treatment for strncpy?

Also, a nit:
void f(char* s, char* d) {
  strncat(d, s, sizeof(d));
}

test.cc:5:17: warning: the value of the size argument in 'strncat' is
too large, might lead to a buffer overflow [-Wstrncat-size]
  strncat(d, s, sizeof(d));
                ^~~~~~~~~

Here, sizeof(d) is not necessarily too large, just wrong.

On Tue, Aug 7, 2012 at 11:36 AM, Anna Zaks <ganna at apple.com> wrote:
> Author: zaks
> Date: Tue Aug  7 13:36:58 2012
> New Revision: 161440
>
> URL: http://llvm.org/viewvc/llvm-project?rev=161440&view=rev
> Log:
> Turn on strncat-size warning implemented a while ago.
>
> Warns on anti-patterns/typos in the 'size' argument to strncat. The
> correct size argument should look like the following:
>  - strncat(dst, src, sizeof(dst) - strlen(dest) - 1);
>
> We warn on:
>  - sizeof(dst)
>  - sizeof(src)
>  - sizeof(dst) - strlen(dst)
>  - sizeof(src) - anything
>
> (This has been implemented in void Sema::CheckStrncatArguments().)
>
> Modified:
>     cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>     cfe/trunk/test/Analysis/cstring-syntax.c
>
> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=161440&r1=161439&r2=161440&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Tue Aug  7 13:36:58 2012
> @@ -373,9 +373,9 @@
>
>  def warn_strncat_large_size : Warning<
>    "the value of the size argument in 'strncat' is too large, might lead to a "
> -  "buffer overflow">, InGroup<StrncatSize>, DefaultIgnore;
> +  "buffer overflow">, InGroup<StrncatSize>, DefaultWarnNoWerror;
>  def warn_strncat_src_size : Warning<"size argument in 'strncat' call appears "
> -  "to be size of the source">, InGroup<StrncatSize>, DefaultIgnore;
> +  "to be size of the source">, InGroup<StrncatSize>, DefaultWarnNoWerror;
>  def note_strncat_wrong_size : Note<
>    "change the argument to be the free space in the destination buffer minus "
>    "the terminating null byte">;
>
> Modified: cfe/trunk/test/Analysis/cstring-syntax.c
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/cstring-syntax.c?rev=161440&r1=161439&r2=161440&view=diff
> ==============================================================================
> --- cfe/trunk/test/Analysis/cstring-syntax.c (original)
> +++ cfe/trunk/test/Analysis/cstring-syntax.c Tue Aug  7 13:36:58 2012
> @@ -1,4 +1,4 @@
> -// RUN: %clang_cc1 -analyze -analyzer-checker=unix.cstring.BadSizeArg -analyzer-store=region -Wno-strlcpy-strlcat-size -Wno-sizeof-array-argument -Wno-sizeof-pointer-memaccess -verify %s
> +// RUN: %clang_cc1 -analyze -analyzer-checker=unix.cstring.BadSizeArg -analyzer-store=region -Wno-strncat-size -Wno-strlcpy-strlcat-size -Wno-sizeof-array-argument -Wno-sizeof-pointer-memaccess -verify %s
>
>  typedef __SIZE_TYPE__ size_t;
>  char  *strncat(char *, const char *, size_t);
>
>
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