From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DFCBDC43381 for ; Wed, 20 Mar 2019 06:37:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B256F2184E for ; Wed, 20 Mar 2019 06:37:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727745AbfCTGhm (ORCPT ); Wed, 20 Mar 2019 02:37:42 -0400 Received: from mx2.suse.de ([195.135.220.15]:40956 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727726AbfCTGhm (ORCPT ); Wed, 20 Mar 2019 02:37:42 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 65ACAAE20; Wed, 20 Mar 2019 06:37:40 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Cc: Yoon Jungyeon , Nikolay Borisov Subject: [PATCh v2 9/9] btrfs: inode: Verify inode mode to avoid NULL pointer dereference Date: Wed, 20 Mar 2019 14:37:17 +0800 Message-Id: <20190320063717.31770-10-wqu@suse.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190320063717.31770-1-wqu@suse.com> References: <20190320063717.31770-1-wqu@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org [BUG] When access a file on a crafted image, btrfs can crash in block layer: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 PGD 136501067 P4D 136501067 PUD 124519067 PMD 0 CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.0.0-rc8-default #252 RIP: 0010:end_bio_extent_readpage+0x144/0x700 Call Trace: blk_update_request+0x8f/0x350 blk_mq_end_request+0x1a/0x120 blk_done_softirq+0x99/0xc0 __do_softirq+0xc7/0x467 irq_exit+0xd1/0xe0 call_function_single_interrupt+0xf/0x20 RIP: 0010:default_idle+0x1e/0x170 [CAUSE] The crafted image has a pretty tricky corruption, the INODE_ITEM has a different type against its parent dir: item 20 key (268 INODE_ITEM 0) itemoff 2808 itemsize 160 generation 13 transid 13 size 1048576 nbytes 1048576 block group 0 mode 121644 links 1 uid 0 gid 0 rdev 0 sequence 9 flags 0x0(none) This mode number 0120000 means it's a soft link. But the dir item think it's still a regular file: item 8 key (264 DIR_INDEX 5) itemoff 3707 itemsize 32 location key (268 INODE_ITEM 0) type FILE transid 13 data_len 0 name_len 2 name: f4 item 40 key (264 DIR_ITEM 51821248) itemoff 1573 itemsize 32 location key (268 INODE_ITEM 0) type FILE transid 13 data_len 0 name_len 2 name: f4 For btrfs symlink, we don't set BTRFS_I(inode)->io_tree.ops and leave it empty, as symlink is only designed to have inlined extent, all handled by tree block read. Thus no need to trigger btrfs_submit_bio_hook() for inline file extent. However for end_bio_extent_readpage() it expects tree->ops populated, as it's reading regular data extent. This causes NULL pointer dereference. [FIX] This patch fixes the problem by 2 directions: - Verify inode mode against its dir item when looking up inode So in btrfs_lookup_dentry() if we find inode mode mismatch with dir item, we error out so that corrupted inode will not be access. - Verify inode mode when getting extent mapping Only regular file should have regular or preallocated extent. If we found regular/preallocated file extent for soft link or whatever, we error out before we submit read bio. With this fix that crafted image can be rejected gracefully: BTRFS critical (device loop0): inode mode mismatch with dir: inode mode=0121644 btrfs type=7 dir type=1 Reported-by: Yoon Jungyeon Link: https://bugzilla.kernel.org/show_bug.cgi?id=202763 Signed-off-by: Qu Wenruo Reviewed-by: Nikolay Borisov --- fs/btrfs/inode.c | 38 ++++++++++++++++++++++++++++-------- fs/btrfs/tests/inode-tests.c | 1 + 2 files changed, 31 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 82fdda8ff5ab..2e16b7779217 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5448,12 +5448,13 @@ void btrfs_evict_inode(struct inode *inode) } /* - * this returns the key found in the dir entry in the location pointer. + * this returns the key found in the dir entry in the location pointer, + * fill @type with BTRFS_FT_*, and return 0. * If no dir entries were found, returns -ENOENT. * If found a corrupted location in dir entry, returns -EUCLEAN. */ static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry, - struct btrfs_key *location) + struct btrfs_key *location, u8 *type) { const char *name = dentry->d_name.name; int namelen = dentry->d_name.len; @@ -5482,6 +5483,8 @@ static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry, __func__, name, btrfs_ino(BTRFS_I(dir)), location->objectid, location->type, location->offset); } + if (!ret) + *type = btrfs_dir_type(path->nodes[0], di); out: btrfs_free_path(path); return ret; @@ -5719,6 +5722,11 @@ static struct inode *new_simple_dir(struct super_block *s, return inode; } +static inline u8 btrfs_inode_type(struct inode *inode) +{ + return btrfs_type_by_mode[(inode->i_mode & S_IFMT) >> S_SHIFT]; +} + struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry) { struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb); @@ -5726,18 +5734,29 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry) struct btrfs_root *root = BTRFS_I(dir)->root; struct btrfs_root *sub_root = root; struct btrfs_key location; + u8 di_type = 0; int index; int ret = 0; if (dentry->d_name.len > BTRFS_NAME_LEN) return ERR_PTR(-ENAMETOOLONG); - ret = btrfs_inode_by_name(dir, dentry, &location); + ret = btrfs_inode_by_name(dir, dentry, &location, &di_type); if (ret < 0) return ERR_PTR(ret); if (location.type == BTRFS_INODE_ITEM_KEY) { inode = btrfs_iget(dir->i_sb, &location, root, NULL); + + /* Do extra check against inode mode with di_type */ + if (btrfs_inode_type(inode) != di_type) { + btrfs_crit(fs_info, +"inode mode mismatch with dir: inode mode=0%o btrfs type=%u dir type=%u", + inode->i_mode, btrfs_inode_type(inode), + di_type); + iput(inode); + return ERR_PTR(-EUCLEAN); + } return inode; } @@ -6342,11 +6361,6 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans, return ERR_PTR(ret); } -static inline u8 btrfs_inode_type(struct inode *inode) -{ - return btrfs_type_by_mode[(inode->i_mode & S_IFMT) >> S_SHIFT]; -} - /* * utility function to add 'inode' into 'parent_inode' with * a give name and a given sequence number. @@ -6864,6 +6878,14 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode, extent_start = found_key.offset; if (extent_type == BTRFS_FILE_EXTENT_REG || extent_type == BTRFS_FILE_EXTENT_PREALLOC) { + /* Only regular file could have regular/prealloc extent */ + if (!S_ISREG(inode->vfs_inode.i_mode)) { + ret = -EUCLEAN; + btrfs_crit(fs_info, + "regular/prealloc extent found for non-regular inode %llu", + btrfs_ino(inode)); + goto out; + } extent_end = extent_start + btrfs_file_extent_num_bytes(leaf, item); diff --git a/fs/btrfs/tests/inode-tests.c b/fs/btrfs/tests/inode-tests.c index af0c8e30d9e2..b01dbcab9eed 100644 --- a/fs/btrfs/tests/inode-tests.c +++ b/fs/btrfs/tests/inode-tests.c @@ -232,6 +232,7 @@ static noinline int test_btrfs_get_extent(u32 sectorsize, u32 nodesize) return ret; } + inode->i_mode = S_IFREG; BTRFS_I(inode)->location.type = BTRFS_INODE_ITEM_KEY; BTRFS_I(inode)->location.objectid = BTRFS_FIRST_FREE_OBJECTID; BTRFS_I(inode)->location.offset = 0; -- 2.21.0