linux-kernel - Re: [PATCH 2/2] mm: Initialize error in shmem_file_aio

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Message-ID: <20140413205029.GO18016@ZenIV.linux.org.uk>
Date:	Sun, 13 Apr 2014 21:50:29 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Steve French <sfrench@...ba.org>, linux-cifs@...r.kernel.org,
	Hugh Dickins <hughd@...gle.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mm: Initialize error in shmem_file_aio_read()

On Sun, Apr 13, 2014 at 08:46:22PM +0200, Geert Uytterhoeven wrote:
> mm/shmem.c: In function ‘shmem_file_aio_read’:
> mm/shmem.c:1414: warning: ‘error’ may be used uninitialized in this function
> 
> If the loop is aborted during the first iteration by one of the two first
> break statements, error will be uninitialized.
> 
> Introduced by commit 6e58e79db8a16222b31fc8da1ca2ac2dccfc4237
> ("introduce copy_page_to_iter, kill loop over iovec in
> generic_file_aio_read()").
> 
> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> ---
> The code is too complex to see if this is an obvious false positive.

Good catch; sadly, it *can* be triggered - read() starting past the EOF
will step into it.  Applied, will push today.
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