From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([59.151.112.132]:2660 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1754755AbaI3Cj0 (ORCPT ); Mon, 29 Sep 2014 22:39:26 -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 s8U2dQhs011252 for ; Tue, 30 Sep 2014 10:39:26 +0800 From: Qu Wenruo To: Subject: [PATCH] btrfs-progs: Don't return any fs_info that contain NULL tree_root or fs_root. Date: Tue, 30 Sep 2014 10:39:22 +0800 Message-ID: <1412044762-2480-1-git-send-email-quwenruo@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-btrfs-owner@vger.kernel.org List-ID: [BUG] btrfsck will segfault if it fails to open the fs tree or tree root. [REPRODUCER] Execute btrfsck on a highly damaged btrfs image. fsfuzz can be used to make a junk btrfs image. [REASON] Current open_ctree() in btrfs-progs support OPEN_CTREE_PARTIAL flag to allow return fs_info even some of the trees is missing. However it is too loose and even allows fs_info containing no tree to be returned. And when it happens, fs_info->fs_root is NULL, close_ctree(fs_info->fs_root) will cause the access to NULL pointer and segfault. [FIX] This patch will add checks for fs_info->tree_root and fs_info->fs_root before return fs_info. Signed-off-by: Qu Wenruo --- disk-io.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/disk-io.c b/disk-io.c index 26a532e..21a3083 100644 --- a/disk-io.c +++ b/disk-io.c @@ -1134,7 +1134,8 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path, return fs_info; out_failed: - if (flags & OPEN_CTREE_PARTIAL) + if (flags & OPEN_CTREE_PARTIAL && + fs_info->tree_root && fs_info->fs_root) return fs_info; out_chunk: btrfs_release_all_roots(fs_info); -- 2.1.1