From: Konstantin Khlebnikov <khlebnikov@openvz.org>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] fs: fix integer overflow in MS_NOUSER definition
Date: Sat, 21 Apr 2012 12:37:19 +0400 [thread overview]
Message-ID: <4F9271BF.4000302@openvz.org> (raw)
In-Reply-To: <20120421062838.GS6871@ZenIV.linux.org.uk>
Al Viro wrote:
> On Sat, Apr 21, 2012 at 09:49:49AM +0400, Konstantin Khlebnikov wrote:
>> MS_NOUSER defined as signed int (1<<31), sb->s_flags declared as unsigned long.
>> So (sb->s_flags& MS_NOUSER) works as (sb->s_flags& 0xffffffff80000000).
>
> ... and it's not a problem since we can't use bits 32 and above anyway -
> unsigned long is 32bit on a lot of platforms. I have no objections to
> making that 1U<<31, but it's not a bug, let alone an integer overflow.
Yes, it's not a bug here, but I not sure about the rest thousand places, where
similar expressions are used. Probably checkpatch should warn about such things.
BTW this patch makes code smaller =)
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-16 (-16)
function old new delta
graft_tree 135 119 -16
prev parent reply other threads:[~2012-04-21 8:37 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-21 5:49 [PATCH] fs: fix integer overflow in MS_NOUSER definition Konstantin Khlebnikov
2012-04-21 6:28 ` Al Viro
2012-04-21 8:37 ` Konstantin Khlebnikov [this message]
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