Btrfs: fix use-after-free problem of the device during device replace
authorMiao Xie <miaox@cn.fujitsu.com>
Wed, 3 Sep 2014 13:35:43 +0000 (21:35 +0800)
committerChris Mason <clm@fb.com>
Wed, 17 Sep 2014 20:38:44 +0000 (13:38 -0700)
commit67a2c45ee7f4f250458279a2e1244679c5d9735c
tree0f1806d2aead6af9629bb701101b75b28863b986
parentadbbb8631beda8e4e5d2c964b8b47e04cfa0a2ae
Btrfs: fix use-after-free problem of the device during device replace

The problem is:
Task0(device scan task) Task1(device replace task)
scan_one_device()
mutex_lock(&uuid_mutex)
device = find_device()
mutex_lock(&device_list_mutex)
lock_chunk()
rm_and_free_source_device
unlock_chunk()
mutex_unlock(&device_list_mutex)
check device

Destroying the target device if device replace fails also has the same problem.

We fix this problem by locking uuid_mutex during destroying source device or
target device, just like the device remove operation.

It is a temporary solution, we can fix this problem and make the code more
clear by atomic counter in the future.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
fs/btrfs/dev-replace.c
fs/btrfs/volumes.c
fs/btrfs/volumes.h