From: Arnd Bergmann <arnd@arndb.de>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
Ingo Molnar <mingo@elte.hu>, David Miller <davem@davemloft.net>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: strict copy_from_user checks issues?
Date: Tue, 5 Jan 2010 14:45:25 +0100 [thread overview]
Message-ID: <201001051445.26149.arnd@arndb.de> (raw)
In-Reply-To: <20100105053443.4a43fc18@infradead.org>
On Tuesday 05 January 2010, Arjan van de Ven wrote:
> > 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.
>
I think it will get inlined on 32 bit machines or without CONFIG_COMPAT,
but not when CONFIG_COMPAT is enabled, because then there are two
call-sites.
The tun_chr_compat_ioctl was only merged in 2.6.33-rc1, so 2.6.32 could
still inline the function all the time.
If the compiler is really smart (haven't tried), it can optimize away
tun_chr_compat_ioctl entirely on i386 and make it an alias to
tun_chr_ioctl, but not on s390 because that uses a nontrivial compat_ptr()
function.
Arnd
next prev parent reply other threads:[~2010-01-05 13:46 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-04 15:43 strict copy_from_user checks issues? Heiko Carstens
2010-01-05 1:43 ` Arjan van de Ven
2010-01-05 7:35 ` Ingo Molnar
2010-01-05 9:48 ` Heiko Carstens
2010-01-05 12:47 ` Arnd Bergmann
2010-01-05 13:19 ` Heiko Carstens
2010-01-05 13:31 ` Arjan van de Ven
2010-01-05 15:22 ` [PATCH] sparc: copy_from_user() should not return -EFAULT Heiko Carstens
2010-01-05 17:27 ` Andi Kleen
2010-01-05 20:47 ` David Miller
2010-01-06 3:20 ` Arjan van de Ven
2010-01-05 17:55 ` Arnd Bergmann
2010-01-06 4:42 ` David Miller
2010-01-05 22:15 ` [tip:x86/urgent] x86: " tip-bot for Heiko Carstens
2010-01-05 13:34 ` strict copy_from_user checks issues? Arjan van de Ven
2010-01-05 13:36 ` Arjan van de Ven
2010-01-05 13:45 ` Arnd Bergmann [this message]
2010-01-05 13:52 ` Arjan van de Ven
2010-01-05 15:20 ` Arnd Bergmann
2010-01-05 21:44 ` H. Peter Anvin
2010-01-07 14:02 ` Arnd Bergmann
2010-01-07 23:57 ` H. Peter Anvin
2010-01-09 0:07 ` Arnd Bergmann
2010-01-09 0:10 ` H. Peter Anvin
2010-01-09 8:01 ` Arnd Bergmann
2010-01-09 20:57 ` H. Peter Anvin
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