linux-ext4 - Re: [PATCH v2] jbd2: fix r_count overflows leading to buffer overflow in journal recovery

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Date:	Thu, 14 May 2015 19:12:42 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Jan Kara <jack@...e.cz>
Cc:	"Darrick J. Wong" <darrick.wong@...cle.com>,
	linux-ext4@...r.kernel.org
Subject: Re: [PATCH v2] jbd2: fix r_count overflows leading to buffer
 overflow in journal recovery

On Thu, May 14, 2015 at 10:48:26PM +0200, Jan Kara wrote:
> On Thu 14-05-15 12:34:24, Darrick J. Wong wrote:
> > The journal revoke block recovery code does not check r_count for
> > sanity, which means that an evil value of r_count could result in
> > the kernel reading off the end of the revoke table and into whatever
> > garbage lies beyond.  This could crash the kernel, so fix that.
> > 
> > However, in testing this fix, I discovered that the code to write
> > out the revoke tables also was not correctly checking to see if the
> > block was full -- the current offset check is fine so long as the
> > revoke table space size is a multiple of the record size, but this
> > is not true when either journal_csum_v[23] are set.
> > 
> > v2: The comparison on the revoke block writer code should allow the
> > revoke block to become totally full.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
>   Looks good. You can add:
> Reviewed-by: Jan Kara <jack@...e.cz>

Thanks, applied.

					- Ted
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