linux-kernel - Re: [PATCH 1/1] fs/omfs/inode.c: replace count*size kzalloc by kcalloc

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Message-ID: <20140625190250.GB399@localhost>
Date:	Wed, 25 Jun 2014 15:02:50 -0400
From:	Bob Copeland <me@...copeland.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Fabian Frederick <fabf@...net.be>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/1] fs/omfs/inode.c: replace count*size kzalloc by
 kcalloc

On Wed, Jun 25, 2014 at 11:27:21AM -0700, Linus Torvalds wrote:
> On Wed, Jun 25, 2014 at 11:17 AM, Fabian Frederick <fabf@...net.be> wrote:
> > kcalloc manages count*sizeof overflow.
> 
> As far as I can tell, any overflow has happened long before, in
> 
>     bitmap_size = DIV_ROUND_UP(sbi->s_num_blocks, 8);
> 
> where 'sbi->s_num_blocks' i san u64, and 'bitmap_size' is an 'int'.
> 
> I don't think the patch is necessarily a bad thing, but I think it
> might be more important to sanity-check that part instead.

Agreed - even though the FS data structures support 64-bit block
count, I've never seen an OMFS fs with more than about 2M blocks
(typical device had 20 gigs w/ 8k blocks).  So it would make
sense to bail in omfs_fill_super if that number is greater than
2^31 or so.

(I am fine with the kcalloc patch too, though.)

-- 
Bob Copeland %% www.bobcopeland.com
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