diff options
| author | Liu Bo <bo.li.liu@oracle.com> | 2018-01-25 11:02:54 -0700 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2018-02-02 16:24:40 +0100 |
| commit | 1a932ef4e47984dee227834667b5ff5a334e4805 (patch) | |
| tree | 9037224c516c5eaaec99d84d7c14c25a8e56a574 /fs/btrfs | |
| parent | e8f1bc1493855e32b7a2a019decc3c353d94daf6 (diff) | |
| download | linux-1a932ef4e47984dee227834667b5ff5a334e4805.tar.bz2 | |
Btrfs: fix use-after-free on root->orphan_block_rsv
I got these from running generic/475,
WARNING: CPU: 0 PID: 26384 at fs/btrfs/inode.c:3326 btrfs_orphan_commit_root+0x1ac/0x2b0 [btrfs]
BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
IP: btrfs_block_rsv_release+0x1c/0x70 [btrfs]
Call Trace:
btrfs_orphan_release_metadata+0x9f/0x200 [btrfs]
btrfs_orphan_del+0x10d/0x170 [btrfs]
btrfs_setattr+0x500/0x640 [btrfs]
notify_change+0x7ae/0x870
do_truncate+0xca/0x130
vfs_truncate+0x2ee/0x3d0
do_sys_truncate+0xaf/0xf0
SyS_truncate+0xe/0x10
entry_SYSCALL_64_fastpath+0x1f/0x96
The race is between btrfs_orphan_commit_root and btrfs_orphan_del,
t1 t2
btrfs_orphan_commit_root btrfs_orphan_del
spin_lock
check (&root->orphan_inodes)
root->orphan_block_rsv = NULL;
spin_unlock
atomic_dec(&root->orphan_inodes);
access root->orphan_block_rsv
Accessing root->orphan_block_rsv must be done before decreasing
root->orphan_inodes.
cc: <stable@vger.kernel.org> v3.12+
Fixes: 703c88e03524 ("Btrfs: fix tracking of orphan inode count")
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/inode.c | 34 |
1 files changed, 21 insertions, 13 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 44a152d8f32f..29b491328f4e 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -3387,6 +3387,11 @@ int btrfs_orphan_add(struct btrfs_trans_handle *trans, ret = btrfs_orphan_reserve_metadata(trans, inode); ASSERT(!ret); if (ret) { + /* + * dec doesn't need spin_lock as ->orphan_block_rsv + * would be released only if ->orphan_inodes is + * zero. + */ atomic_dec(&root->orphan_inodes); clear_bit(BTRFS_INODE_ORPHAN_META_RESERVED, &inode->runtime_flags); @@ -3401,12 +3406,17 @@ int btrfs_orphan_add(struct btrfs_trans_handle *trans, if (insert >= 1) { ret = btrfs_insert_orphan_item(trans, root, btrfs_ino(inode)); if (ret) { - atomic_dec(&root->orphan_inodes); if (reserve) { clear_bit(BTRFS_INODE_ORPHAN_META_RESERVED, &inode->runtime_flags); btrfs_orphan_release_metadata(inode); } + /* + * btrfs_orphan_commit_root may race with us and set + * ->orphan_block_rsv to zero, in order to avoid that, + * decrease ->orphan_inodes after everything is done. + */ + atomic_dec(&root->orphan_inodes); if (ret != -EEXIST) { clear_bit(BTRFS_INODE_HAS_ORPHAN_ITEM, &inode->runtime_flags); @@ -3438,28 +3448,26 @@ static int btrfs_orphan_del(struct btrfs_trans_handle *trans, { struct btrfs_root *root = inode->root; int delete_item = 0; - int release_rsv = 0; int ret = 0; - spin_lock(&root->orphan_lock); if (test_and_clear_bit(BTRFS_INODE_HAS_ORPHAN_ITEM, &inode->runtime_flags)) delete_item = 1; + if (delete_item && trans) + ret = btrfs_del_orphan_item(trans, root, btrfs_ino(inode)); + if (test_and_clear_bit(BTRFS_INODE_ORPHAN_META_RESERVED, &inode->runtime_flags)) - release_rsv = 1; - spin_unlock(&root->orphan_lock); + btrfs_orphan_release_metadata(inode); - if (delete_item) { + /* + * btrfs_orphan_commit_root may race with us and set ->orphan_block_rsv + * to zero, in order to avoid that, decrease ->orphan_inodes after + * everything is done. + */ + if (delete_item) atomic_dec(&root->orphan_inodes); - if (trans) - ret = btrfs_del_orphan_item(trans, root, - btrfs_ino(inode)); - } - - if (release_rsv) - btrfs_orphan_release_metadata(inode); return ret; } |