linux-kernel - Re: [PATCH 4.9 37/95] ext4: add validity checks for bitmap block numbers

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Date:   Mon, 23 Apr 2018 09:13:50 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     "Theodore Y. Ts'o" <tytso@....edu>,
        Ben Hutchings <ben@...adent.org.uk>, stable@...r.kernel.org,
        Wen Xu <wen.xu@...ech.edu>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4.9 37/95] ext4: add validity checks for bitmap block
 numbers

On Mon, Apr 23, 2018 at 02:03:52AM -0400, Theodore Y. Ts'o wrote:
> On Sun, Apr 22, 2018 at 10:54:23PM +0100, Ben Hutchings wrote:
> > >  	offset = blk - group_first_block;
> > > -	if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
> > > +	if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize ||
> > > +	    !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
> > 
> > Isn't sb->s_blocksize a count of bytes?  If so, doesn't that mean that
> > we should be comparing with sb->s_blocksize * 8?
> 
> Yes, nice catch, Ben!  Can we temporarily drop this patch from the
> stable queue until I can get a fix in?
> 
> In practice this shouldn't be a problem because of the default ext4
> layout with flex_bg.  But we should definitely get this fixed before
> we let this flow into the stable kernel.

Now dropped from all queues.  When you submit the fix, can you also tag
it for stable so I know to pick this one back up?

thanks,

greg k-h