From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([59.151.112.132]:38015 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753121AbaJWHbR convert rfc822-to-8bit (ORCPT ); Thu, 23 Oct 2014 03:31:17 -0400 Received: from G08CNEXCHPEKD02.g08.fujitsu.local (localhost.localdomain [127.0.0.1]) by edo.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id s9N7VAPh013091 for ; Thu, 23 Oct 2014 15:31:10 +0800 Message-ID: <5448AEC3.2080308@cn.fujitsu.com> Date: Thu, 23 Oct 2014 15:31:15 +0800 From: Qu Wenruo MIME-Version: 1.0 To: Subject: Re: [PATCH 1/2] btrfs: Add more check before read_extent_buffer() to avoid read overflow. References: <1411012892-17481-1-git-send-email-quwenruo@cn.fujitsu.com> In-Reply-To: <1411012892-17481-1-git-send-email-quwenruo@cn.fujitsu.com> Content-Type: text/plain; charset="utf-8"; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: I'm sorry that this patch is not needed since inline extent will not go into this routine, so no overflow. Please ignore the patch, Thanks, Qu -------- Original Message -------- Subject: [PATCH 1/2] btrfs: Add more check before read_extent_buffer() to avoid read overflow. From: Qu Wenruo To: Date: 2014年09月18日 12:01 > Before this patch, when replay_one_extent() find an existing file > extent item, btrfs will call read_extent_buffer() to read out the file > extent. > However it lacks enough check, and may read out the inline file extent > using the wrong size(currently it always uses > sizeof(btrfs_file_extent_item)) > > If a inline file extent's size is smaller than normal file extent > size(53 bytes) and unfortunately the inline file extent lies at the end > of a full leaf, WARN_ON in read_extent_buffer() will be triggered. > > This patch will check the file extent type before calling > read_extent_buffer(), since the if the logged one and the existing one > are all preallocated/regular file extent item, their size must be > sizeof(struct btrfs_file_extent_item) and will avoid the read overflow. > > Signed-off-by: Qu Wenruo > --- > fs/btrfs/tree-log.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c > index 7e0e6e3..1ea2b10 100644 > --- a/fs/btrfs/tree-log.c > +++ b/fs/btrfs/tree-log.c > @@ -620,6 +620,8 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans, > existing = btrfs_item_ptr(leaf, path->slots[0], > struct btrfs_file_extent_item); > > + if (btrfs_file_extent_type(leaf, existing) != found_type) > + goto no_compare; > read_extent_buffer(eb, &cmp1, (unsigned long)item, > sizeof(cmp1)); > read_extent_buffer(leaf, &cmp2, (unsigned long)existing, > @@ -634,6 +636,7 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans, > goto out; > } > } > +no_compare: > btrfs_release_path(path); > > /* drop any overlapping extents */