From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (Postfix) with ESMTP id 5686F7F54 for ; Thu, 6 Feb 2014 00:17:31 -0600 (CST) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay3.corp.sgi.com (Postfix) with ESMTP id 068B2AC004 for ; Wed, 5 Feb 2014 22:17:27 -0800 (PST) Received: from ipmail06.adl2.internode.on.net (ipmail06.adl2.internode.on.net [150.101.137.129]) by cuda.sgi.com with ESMTP id 6hYyQTpZpOHz0Zo1 for ; Wed, 05 Feb 2014 22:17:26 -0800 (PST) Received: from disappointment.disaster.area ([192.168.1.110] helo=disappointment) by dastard with esmtp (Exim 4.76) (envelope-from ) id 1WBIH4-0007IB-Ok for xfs@oss.sgi.com; Thu, 06 Feb 2014 17:17:22 +1100 Received: from dave by disappointment with local (Exim 4.80) (envelope-from ) id 1WBIH4-00081j-Nb for xfs@oss.sgi.com; Thu, 06 Feb 2014 17:17:22 +1100 From: Dave Chinner Subject: [PATCH] xfs: ensure correct log item buffer alignment Date: Thu, 6 Feb 2014 17:17:22 +1100 Message-Id: <1391667442-30822-1-git-send-email-david@fromorbit.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: xfs@oss.sgi.com From: Dave Chinner On 32 bit platforms, the log item vector headers are not 64 bit aligned or sized. hence if we don't take care to align them correctly or pad the buffer appropriately for 8 byte alignment, we can end up with alignment issues when accessing the user buffer directly as a structure. To solve this, simply pad the buffer headers to 64 bit offset so that the data section is always 8 byte aligned. Signed-off-by: Dave Chinner --- fs/xfs/xfs_log_cil.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c index cdebd83..4ef6fdb 100644 --- a/fs/xfs/xfs_log_cil.c +++ b/fs/xfs/xfs_log_cil.c @@ -205,16 +205,25 @@ xlog_cil_insert_format_items( /* * We 64-bit align the length of each iovec so that the start * of the next one is naturally aligned. We'll need to - * account for that slack space here. + * account for that slack space here. Then round nbytes up + * to 64-bit alignment so that the initial buffer alignment is + * easy to calculate and verify. */ nbytes += niovecs * sizeof(uint64_t); + nbytes = round_up(nbytes, sizeof(uint64_t)); /* grab the old item if it exists for reservation accounting */ old_lv = lip->li_lv; - /* calc buffer size */ - buf_size = sizeof(struct xfs_log_vec) + nbytes + - niovecs * sizeof(struct xfs_log_iovec); + /* + * The data buffer needs to start 64-bit aligned, so round up + * that space to ensure we can align it appropriately and not + * overrun the buffer. + */ + buf_size = nbytes + + round_up((sizeof(struct xfs_log_vec) + + niovecs * sizeof(struct xfs_log_iovec)), + sizeof(uint64_t)); /* compare to existing item size */ if (lip->li_lv && buf_size <= lip->li_lv->lv_size) { @@ -251,6 +260,8 @@ xlog_cil_insert_format_items( /* The allocated data region lies beyond the iovec region */ lv->lv_buf_len = 0; lv->lv_buf = (char *)lv + buf_size - nbytes; + ASSERT(IS_ALIGNED((unsigned long)lv->lv_buf, sizeof(uint64_t))); + lip->li_ops->iop_format(lip, lv); insert: ASSERT(lv->lv_buf_len <= nbytes); -- 1.8.4.rc3 _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs