[Python-Dev] cpython: Use strncat() instead of strcat() to silence some warnings.

[Serhiy Storchaka]

20.07.13 15:36, Antoine Pitrou написав(ла):
> On Sat, 20 Jul 2013 15:23:46 +0300
> Serhiy Storchaka <storchaka at gmail.com> wrote:
>> 20.07.13 15:12, christian.heimes написав(ла):
>>> http://hg.python.org/cpython/rev/c92f4172d122
>>> changeset:   84723:c92f4172d122
>>> user:        Christian Heimes <christian at cheimes.de>
>>> date:        Sat Jul 20 14:11:28 2013 +0200
>>> summary:
>>>     Use strncat() instead of strcat() to silence some warnings.
>>> CID 486616, CID 486617, CID 486615
>>>
> [...]
>>
>> This will wrong when strlen(fname) is 30. strncat() will copy only 30
>> bytes, without terminal NUL.
>
> So, for the record, this is roughly how Rasmus Lerdorf introduced a
> security hole in PHP 5.3.7:
>
>
> "For people asking me out-of-band what the screw-up was, it was pretty
> simple. I changed this code:
>
> memcpy(passwd, MD5_MAGIC, MD5_MAGIC_LEN);
> strlcpy(passwd + MD5_MAGIC_LEN, sp, sl + 1);
> strcat(passwd, "$");
>
> to:
>
> memcpy(passwd, MD5_MAGIC, MD5_MAGIC_LEN);
> strlcpy(passwd + MD5_MAGIC_LEN, sp, sl + 1);
> strlcat(passwd, "$", 1);
>
> **because the Coverity static analyzer warned about using strcat**
> [emphasis mine] and we generally try to avoid naked strcat/strcpy in the
> codebase even though in this case it is safe to do."
>
> https://plus.google.com/113641248237520845183/posts/g68d9RvRA1i

strlcat != strncat. strlcat(dst, src, 1) actually do nothing.