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Date: Sat, 22 Oct 2011 04:56:21 +0400
From: Solar Designer <>
Subject: Re: hardlink(1) has buffer overflows, is unsafe on changing trees

On Fri, Oct 21, 2011 at 03:29:41PM +0530, Huzaifa Sidhpurwala wrote:
> On 10/20/2011 08:27 PM, Josh Bressers wrote:
> >>The hardlink(1) program from Fedora is susceptible to buffer overflows of
> >>fixed-size nambuf1 and nambuf2 buffers when run on a tree with deeply
> >>nested directories and/or with long directory or file names.  I was able
> >>to reproduce the problem (got a segfault) by running the program on a
> >>directory containing 20 nested directories with 250-character names.
> >
> >CVE-2011-3630 hardlink buffer overflows
> >
> FORTIFY_SOURCE should really be able to catch this buffer overflow.
> The buffer being overflown here in in BSS, But strcat() is used to 
> append to this buffer and __builtin___strcat_chk catches it, resulting 
> in the program being terminated.

Besides the strcpy() and strcat() with obviously known target buffer
size, there are also:

          strcpy (stpcpy (nambuf2, n2), ".$$$___cleanit___$$$");


      strcpy (p, di->d_name);

where "p" points somewhere inside nambuf1.

These will just need different reproducers.


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