linux-kernel - Re: [Oops 1/2]Something wrong with copy_from_user() function - possible false positive due bug in gcc 4.6

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Message-ID: <20110531003826.GD14366@smp.if.uj.edu.pl>
Date:	Tue, 31 May 2011 02:38:26 +0200
From:	"Witold Baryluk" <baryluk@....if.uj.edu.pl>
To:	Jiri Kosina <jkosina@...e.cz>
Cc:	Harry Wei <jiaweiwei.xiyou@...il.com>,
	Andy Lutomirski <luto@....EDU>, Greg KH <greg@...ah.com>,
	Andres More <more.andres@...il.com>,
	Joe Perches <joe@...ches.com>, linux-kernel@...r.kernel.org,
	devel@...verdev.osuosl.org, Ilia Mirkin <imirkin@...m.mit.edu>
Subject: Re: [Oops 1/2]Something wrong with copy_from_user() function -
 possible false positive due bug in gcc 4.6

Hi.

You my wantto look here

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48880
and
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46639

It is regression in gcc 4.6

Particulry this error happens in binfmt_misc.c file.
gcc 4.6 errornously print error in this file.

However I could not find such behavior
nowhere in rest of kernel. But it can still
be a case If you use gcc 4.6.

If you are using gcc 4.5 or older, it is probably
genuine error, or someone is using a destination
buffer which is unknown size and gcc cannot
prove it is big enaugh to hold data.

-- 
Witold Baryluk

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