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

[Anna Zaks]

On Aug 7, 2012, at 12:01 PM, Matt Beaumont-Gay wrote:

> Should we have similar treatment for strncpy?

You are right. It would be worthwhile to add a warning for these as well:

strncpy(dst, src, sizeof(dst)); // fixit: "sizeof(dst)" -> "sizeof(dst)-1"

strncpy(dst, src, sizeof(src));

Thanks,
Anna.

> 
> 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);
>> 
>> 
>> _______________________________________________
>> cfe-commits mailing list
>> cfe-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits