linux-kernel - Re: "elf core dump: fix get_user use" breaks mips compilation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 16 Feb 2009 23:32:16 +0000
From:	Ralf Baechle <ralf@...ux-mips.org>
To:	Martin Michlmayr <tbm@...ius.com>
Cc:	Roland McGrath <roland@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: "elf core dump: fix get_user use" breaks mips compilation

On Mon, Feb 16, 2009 at 01:01:36PM +0100, Martin Michlmayr wrote:

> Hi Roland,
> 
> Your change "elf core dump: fix get_user use"  (which made it into
> 2.6.28.5) breaks the compilation on MIPS (which sets -Werror):
> 
>   CC      arch/mips/kernel/binfmt_elfn32.o
> cc1: warnings being treated as errors
> arch/mips/kernel/../../../fs/binfmt_elf.c: In function ‘vma_dump_size’:
> arch/mips/kernel/../../../fs/binfmt_elf.c:1202: warning: ‘word’ may be used uninitialized in this function
> make[1]: *** [arch/mips/kernel/binfmt_elfn32.o] Error 1

Partially expanding get_user() the code basically does this:

	int word;

	if (access_ok(...))
		__get_user(word, header);
	else
		word = 0;

And gcc is unable to figure out that word will always be assigned to by
both paths of the if statement.  Older gcc versions used to have that
problem.  I can't reproduce your problem with gcc 4.3.2 and I assume
you're using something older than that?

  Ralf
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/