From: Andrew Morton <akpm00@gmail.com>
To: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-next@vger.kernel.org, linux-kernel@vger.kernel.org,
Stephen Boyd <sboyd@codeaurora.org>, Ingo Molnar <mingo@elte.hu>,
"H. Peter Anvin" <hpa@zytor.com>,
David Miller <davem@davemloft.net>, <netdev@vger.kernel.org>
Subject: Re: linux-next: build failure after merge of the akpm tree
Date: Thu, 29 Sep 2011 23:02:26 -0700 [thread overview]
Message-ID: <20110929230226.5fed4095.akpm00@gmail.com> (raw)
In-Reply-To: <20110930153255.6e3a0d6dc7758b7fb5561fc6@canb.auug.org.au>
On Fri, 30 Sep 2011 15:32:55 +1000 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> Hi Andrew,
>
> After merging the akpm tree, today's linux-next build (x86_64 allmodconfig)
> failed like this:
>
> In file included from arch/x86/include/asm/uaccess.h:575:0,
> from include/net/checksum.h:25,
> from include/linux/skbuff.h:28,
> from include/linux/icmpv6.h:82,
> from net/compat.c:19:
> In function 'copy_from_user',
> inlined from 'compat_sys_socketcall' at net/compat.c:793:20:
> arch/x86/include/asm/uaccess_64.h:64:26: error: call to 'copy_from_user_overflow' declared with attribute error: copy_from_user() buffer size is not provably correct
>
> Caused by commit 15e19cbbbf2a ("x86: implement strict user copy checks
> for x86_64") when built with gcc 4.6.0. This does not fail when built
> with 4.5.2.
This:
extern void copy_from_user_overflow(void)
#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
__compiletime_error("copy_from_user() buffer size is not provably correct")
#else
__compiletime_warning("copy_from_user() buffer size is not provably correct")
#endif
presumably CONFIG_DEBUG_STRICT_USER_COPY_CHECKS=y, so it's doing what
we asked it to do.
> The problem here is that the length parameter to copy_from_user() is
> obtained by indexing into an array of sizes. Making the array const
> does not help (obviously, since the index is not known at compile time
> anyway).
>
> Maybe I need a newer compiler. For today I have gone back to my 4.5.2
> compiler.
That patch is a PITA. I've been waiting for some saviour to come along
and fix all the warnings it emits before proceeding with it. As I am
apparently saviourless I shall hide that patch from the mm->linux-next
drop, so only I get to suffer its effects.
next prev parent reply other threads:[~2011-09-30 6:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-30 5:32 linux-next: build failure after merge of the akpm tree Stephen Rothwell
2011-09-30 6:02 ` Andrew Morton [this message]
2011-10-04 7:44 ` Stephen Rothwell
-- strict thread matches above, loose matches on Subject: below --
2013-02-11 7:13 Stephen Rothwell
2013-02-11 12:04 ` Amir Vadai
2013-02-20 6:28 Stephen Rothwell
2017-06-30 6:32 Stephen Rothwell
2017-07-03 8:14 ` Stephen Rothwell
2017-07-03 8:57 ` David Miller
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