From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zheng Liu Subject: [PATCH v2 1/5] ext4: improve ext4_es_can_be_merged() to avoid a potential overflow Date: Wed, 6 Mar 2013 22:17:11 +0800 Message-ID: <1362579435-6333-2-git-send-email-wenqing.lz@taobao.com> References: <1362579435-6333-1-git-send-email-wenqing.lz@taobao.com> Cc: Zheng Liu , "Theodore Ts'o" , Dmitry Monakhov To: linux-ext4@vger.kernel.org Return-path: Received: from mail-pb0-f48.google.com ([209.85.160.48]:60226 "EHLO mail-pb0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756240Ab3CFOCP (ORCPT ); Wed, 6 Mar 2013 09:02:15 -0500 Received: by mail-pb0-f48.google.com with SMTP id wy12so6004437pbc.7 for ; Wed, 06 Mar 2013 06:02:15 -0800 (PST) In-Reply-To: <1362579435-6333-1-git-send-email-wenqing.lz@taobao.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: From: Zheng Liu This commit tries to improve ext4_es_can_be_merged. We check the length of extent to avoid a potential overflow. Signed-off-by: Zheng Liu Cc: "Theodore Ts'o" Cc: Dmitry Monakhov --- fs/ext4/extents_status.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c index 95796a1..dc4e4c5 100644 --- a/fs/ext4/extents_status.c +++ b/fs/ext4/extents_status.c @@ -333,17 +333,33 @@ static void ext4_es_free_extent(struct inode *inode, struct extent_status *es) static int ext4_es_can_be_merged(struct extent_status *es1, struct extent_status *es2) { - if (es1->es_lblk + es1->es_len != es2->es_lblk) + __u64 es1_len, es2_len, max_len; + + if (ext4_es_status(es1) ^ ext4_es_status(es2)) return 0; - if (ext4_es_status(es1) != ext4_es_status(es2)) + max_len = 0xFFFFFFFFULL; + es1_len = es1->es_len; + es2_len = es2->es_len; + + if (es1_len + es2_len > max_len) return 0; - if ((ext4_es_is_written(es1) || ext4_es_is_unwritten(es1)) && - (ext4_es_pblock(es1) + es1->es_len != ext4_es_pblock(es2))) + if (es1->es_lblk + es1_len != es2->es_lblk) return 0; - return 1; + if ((ext4_es_is_written(es1) || ext4_es_is_unwritten(es1)) && + (ext4_es_pblock(es1) + es1_len == ext4_es_pblock(es2))) + return 1; + + if (ext4_es_is_hole(es1)) + return 1; + + /* we need to check delayed extent is without unwritten status */ + if (ext4_es_is_delayed(es1) && !ext4_es_is_unwritten(es1)) + return 1; + + return 0; } static struct extent_status * -- 1.7.12.rc2.18.g61b472e