linux-kernel - Re: strict copy_from

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Message-ID: <20100105053443.4a43fc18@infradead.org>
Date:	Tue, 5 Jan 2010 05:34:43 -0800
From:	Arjan van de Ven <arjan@...radead.org>
To:	Heiko Carstens <heiko.carstens@...ibm.com>
Cc:	Ingo Molnar <mingo@...e.hu>, David Miller <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: strict copy_from_user checks issues?

On Tue, 5 Jan 2010 10:48:57 +0100
Heiko Carstens <heiko.carstens@...ibm.com> wrote:

> 
> An allyesconfig triggers 52 warnings on s390 (see below). I just
> checked a few but all of them looked like false positives.

hmm I wonder why s390 gcc is so different.... if the s390 gcc isn't
so good at proving things, maybe it's wrong to warn on s390?



> In file included
> from /home2/heicarst/cfu/arch/s390/include/asm/mmu_context.h:13,
> from /home2/heicarst/cfu/arch/s390/include/asm/elf.h:133, from
> include/linux/elf.h:7, from include/linux/module.h:14, from
> drivers/net/tun.c:42: In function 'copy_from_user',
>     inlined from '__tun_chr_ioctl' at drivers/net/tun.c:1124:
> /home2/heicarst/cfu/arch/s390/include/asm/uaccess.h:299: warning:
> call to 'copy_from_user_overflow' declared with attribute warning:
> copy_from_user() buffer size is not provably correct

this one is ... interesting btw... I have trouble myself finding where
the check is done... so I can understand gcc having trouble too.





-- 
Arjan van de Ven 	Intel Open Source Technology Centre
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