From: Manish Katiyar Subject: Re: [PATCH] : make sure the buffer head members are zeroed out before using them. Date: Mon, 26 Jan 2009 18:03:19 +0530 Message-ID: References: <20090126122907.GA18681@atrey.karlin.mff.cuni.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: ext4 , "Theodore Ts'o" , cmm@us.ibm.com To: Jan Kara Return-path: Received: from ti-out-0910.google.com ([209.85.142.191]:39031 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751056AbZAZMdV (ORCPT ); Mon, 26 Jan 2009 07:33:21 -0500 Received: by ti-out-0910.google.com with SMTP id b6so3339154tic.23 for ; Mon, 26 Jan 2009 04:33:19 -0800 (PST) In-Reply-To: <20090126122907.GA18681@atrey.karlin.mff.cuni.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: 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. Thanks - Manish > > 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 >