From: Jan Kara Subject: Re: [PATCH] : make sure the buffer head members are zeroed out before using them. Date: Mon, 26 Jan 2009 13:29:07 +0100 Message-ID: <20090126122907.GA18681@atrey.karlin.mff.cuni.cz> References: 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 atrey.karlin.mff.cuni.cz ([195.113.26.193]:54200 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750768AbZAZM3J (ORCPT ); Mon, 26 Jan 2009 07:29:09 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: > 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. Honza > > Signed-off-by : Manish Katiyar > > --- > > fs/ext2/super.c | 4 ++-- > > 1 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/fs/ext2/super.c b/fs/ext2/super.c > > index da8bdea..d10aa44 100644 > > --- a/fs/ext2/super.c > > +++ b/fs/ext2/super.c > > @@ -1327,7 +1327,7 @@ static ssize_t ext2_quota_read(struct > > super_block *sb, int type, char *data, > > tocopy = sb->s_blocksize - offset < toread ? > > sb->s_blocksize - offset : toread; > > > > - tmp_bh.b_state = 0; > > + memset(&tmp_bh, 0, sizeof(struct buffer_head)); > > err = ext2_get_block(inode, blk, &tmp_bh, 0); > > if (err < 0) > > return err; > > @@ -1366,7 +1366,7 @@ static ssize_t ext2_quota_write(struct > > super_block *sb, int type, > > tocopy = sb->s_blocksize - offset < towrite ? > > sb->s_blocksize - offset : towrite; > > > > - tmp_bh.b_state = 0; > > + memset(&tmp_bh, 0, sizeof(struct buffer_head)); > > err = ext2_get_block(inode, blk, &tmp_bh, 1); > > if (err < 0) > > goto out; > > -- > > 1.5.4.3 > > > > > > Thanks - > > Manish > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Jan Kara SuSE CR Labs