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Date: Mon, 14 Dec 2009 11:06:14 +0100
From: Michal Marek <mmarek@suse.cz>
Subject: Re: [PATCH] modpost: fix segfault with short symbol names
Message-ID: <20091214100613.GA21769@sepie.suse.cz>
References: <1260615744-23165-1-git-send-email-mmarek@suse.cz>
 <BECBC631-3E9B-48EF-AA08-5C37806C4A7D@kernel.crashing.org>
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To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>, linux-kbuild@vger.kernel.org

On Sat, Dec 12, 2009 at 04:26:20PM +0100, Segher Boessenkool wrote:
> >memcmp() is wrong here, the symbol name can be shorter than
> >KSYMTAB_PFX
> >or CRC_PFX.
> 
> >-		if (memcmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) {
> >+		if (strncmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) {
> 
> This doesn't change anything.  In both cases the function will return 0
> only if all strlen(CRC_PFX) chars match, and in both cases it can access
> strlen(CRC_PFX) chars (strncmp() is allowed to access characters after
> the first \0 just fine).

str(n)cmp is not allowed to access characters past the NUL byte.

Michal