From: Jan Kara Subject: Re: [PATCH] : make sure the buffer head members are zeroed out before using them. Date: Mon, 26 Jan 2009 14:00:16 +0100 Message-ID: <20090126130016.GC2726@duck.suse.cz> References: <20090126122907.GA18681@atrey.karlin.mff.cuni.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: ext4 , Theodore Ts'o , cmm@us.ibm.com To: Manish Katiyar Return-path: Received: from styx.suse.cz ([82.119.242.94]:37131 "EHLO mail.suse.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750926AbZAZNAT (ORCPT ); Mon, 26 Jan 2009 08:00:19 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon 26-01-09 18:18:19, Manish Katiyar wrote: > On Mon, Jan 26, 2009 at 6:03 PM, Manish Katiyar wrote: > > On Mon, Jan 26, 2009 at 5:59 PM, Jan Kara wrote: > >>> On Tue, Jan 20, 2009 at 10:36 PM, Manish Katiyar wrote: > >>> > ext2_quota_read doesn't bzeroes tmp_bh before calling ext2_get_block() > >>> > where we access the b_size of it. Since it is a local variable it > >>> > might contain some garbage. Make sure it is filled with zero before > >>> > passing. > >>> > >>> Hi Ted/mingming, > >>> > >>> Any feedback on this ?? > >> Ops, sorry. I wanted to reply but first I wanted to research more > >> whether we can set b_size to 0 and then forgot about it. Looking into > >> other code (e.g. in fs/mpage.c or fs/buffer.c) I think it would be > >> better to set b_size to sb->s_blocksize and be done with that. Mapping > >> code does not need anything else set to a deterministic value so using > >> memset is a bit overkill. > > > > Thanks Jan for your comments. Yes memset is an overkill. I did it just > > because other users of ext2_get_block were doing the same way. Will > > rework the patch with setting b_size as blocksize and send again. > > Here is the updated patch. compile tested. > > Signed-off-by : Manish Katiyar Yes, now it looks fine. Thanks for the fix. Acked-by: Jan Kara Honza > --- > fs/ext2/super.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/fs/ext2/super.c b/fs/ext2/super.c > index da8bdea..2a1c0c6 100644 > --- a/fs/ext2/super.c > +++ b/fs/ext2/super.c > @@ -1328,6 +1328,7 @@ static ssize_t ext2_quota_read(struct > super_block *sb, int type, char *data, > sb->s_blocksize - offset : toread; > > tmp_bh.b_state = 0; > + tmp_bh.b_size = sb->s_blocksize; > err = ext2_get_block(inode, blk, &tmp_bh, 0); > if (err < 0) > return err; > @@ -1367,6 +1368,7 @@ static ssize_t ext2_quota_write(struct > super_block *sb, int type, > sb->s_blocksize - offset : towrite; > > tmp_bh.b_state = 0; > + tmp_bh.b_size = sb->s_blocksize; > err = ext2_get_block(inode, blk, &tmp_bh, 1); > if (err < 0) > goto out; > -- > 1.5.4.3 -- Jan Kara SUSE Labs, CR