From: Manish Katiyar Subject: Re: [PATCH] : make sure the buffer head members are zeroed out before using them. Date: Mon, 26 Jan 2009 18:18:19 +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 ([209.85.142.184]:40726 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751018AbZAZMsW (ORCPT ); Mon, 26 Jan 2009 07:48:22 -0500 Received: by ti-out-0910.google.com with SMTP id b6so3339638tic.23 for ; Mon, 26 Jan 2009 04:48:19 -0800 (PST) In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: 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 --- 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 Thanks - Manish > > 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 >> >