Re: [PATCH] fs: fix integer overflow in MS_NOUSER definition

From: Konstantin Khlebnikov
Date: Sat Apr 21 2012 - 04:37:38 EST

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
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