Bug 337415 – net-analyzer/fwlogwatch _FORTIFY_SOURCE indicates presence of overflow

• Product: Gentoo Linux
• Status: RESOLVED FIXED

[Description Diego Elio Pettenò (RETIRED) 2010-09-15 06:46:22 UTC]

You're receiving this bug because the package in Summary has produced _FORTIFY_SOURCE related warnings indicating the presence of a sure overflow in a static buffer.

Even though this is not always an indication of a security problem it might even be. So please check this out ASAP.

By the way, _FORTIFY_SOURCE is disabled when you disable optimisation, so don't try finding out the cause using -O0.

Thanks,
Your friendly neighborhood tinderboxer

[Comment 1 Diego Elio Pettenò (RETIRED) 2010-09-15 06:46:59 UTC]

Created attachment 247390 [details]
Build log

[Comment 2 Jeroen Roovers (RETIRED) 2010-11-30 21:02:22 UTC]

1.2 fairs no better:

In file included from /usr/include/string.h:640,
                 from response.c:7:
In function ‘strncat’,
    inlined from ‘react’ at response.c:120:
/usr/include/bits/string3.h:154: warning: call to __builtin___strncat_chk might overflow destination buffer
In function ‘strncat’,
    inlined from ‘react’ at response.c:124:
/usr/include/bits/string3.h:154: warning: call to __builtin___strncat_chk might overflow destination buffer
In function ‘strncat’,
    inlined from ‘react’ at response.c:131:
/usr/include/bits/string3.h:154: warning: call to __builtin___strncat_chk might overflow destination buffer
In function ‘strncat’,
    inlined from ‘react’ at response.c:138:
/usr/include/bits/string3.h:154: warning: call to __builtin___strncat_chk might overflow destination buffer
In function ‘strncat’,
    inlined from ‘react’ at response.c:145:
/usr/include/bits/string3.h:154: warning: call to __builtin___strncat_chk might overflow destination buffer

[Comment 3 Jeroen Roovers (RETIRED) 2011-08-01 02:31:23 UTC]

Fixed in 1.2-r1. Patch sent upstream. Now what?

[Comment 4 Jeroen Roovers (RETIRED) 2011-08-01 17:26:51 UTC]

Upstream agrees that the patch is superficially correct but glosses over the fact that the buffer in question isn't actually ever overflown, since the source is never larger than the destination, but that _FORTIFY_SOURCE simply doesn't check that context well enough and simply compares the buffer size to write with the size of the destination buffer, which is indeed off by one, but not to any effect.

[Comment 5 Jeroen Roovers (RETIRED) 2011-12-16 16:48:07 UTC]

Fixed in 1.3.