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Date: Sat, 22 Oct 2011 05:19:03 +0400
From: Solar Designer <solar@...nwall.com>
To: oss-security@...ts.openwall.com
Subject: Re: hardlink(1) has buffer overflows, is unsafe on changing trees

On Sat, Oct 22, 2011 at 04:56:21AM +0400, Solar Designer wrote:
>       strcpy (p, di->d_name);
> 
> where "p" points somewhere inside nambuf1.
> 
> These will just need different reproducers.

Actually, I think my proposed reproducer (many nested 250-char dirs)
triggers this one and not the strcat().  On one build, hardlink then
crashes after dereferencing the "dirs" pointer, which happens to be
overwritten with a directory name.  On another build (different gcc
version and arch), hardlink does not crash (although I think it would on
even more nested directories), but reports a ridiculous directory count
(so "ndirs" is overwritten).  -D_FORTIFY_SOURCE=2 didn't make a
difference here (different program binary, same observed behavior).

Alexander

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