diff options
| author | Mike Snitzer <snitzer@kernel.org> | 2023-04-17 11:59:56 -0400 |
|---|---|---|
| committer | Mike Snitzer <snitzer@kernel.org> | 2023-04-17 12:15:55 -0400 |
| commit | 3d32aaa7e66d5c1479a3c31d6c2c5d45dd0d3b89 (patch) | |
| tree | d1f9683569456ae774b090da35c7a32da34cc118 /drivers/md | |
| parent | f7995089c508a5a11b0491c7b348d5c07217a4e8 (diff) | |
dm ioctl: fix nested locking in table_clear() to remove deadlock concern
syzkaller found the following problematic rwsem locking (with write
lock already held):
down_read+0x9d/0x450 kernel/locking/rwsem.c:1509
dm_get_inactive_table+0x2b/0xc0 drivers/md/dm-ioctl.c:773
__dev_status+0x4fd/0x7c0 drivers/md/dm-ioctl.c:844
table_clear+0x197/0x280 drivers/md/dm-ioctl.c:1537
In table_clear, it first acquires a write lock
https://elixir.bootlin.com/linux/v6.2/source/drivers/md/dm-ioctl.c#L1520
down_write(&_hash_lock);
Then before the lock is released at L1539, there is a path shown above:
table_clear -> __dev_status -> dm_get_inactive_table -> down_read
https://elixir.bootlin.com/linux/v6.2/source/drivers/md/dm-ioctl.c#L773
down_read(&_hash_lock);
It tries to acquire the same read lock again, resulting in the deadlock
problem.
Fix this by moving table_clear()'s __dev_status() call to after its
up_write(&_hash_lock);
Cc: stable@vger.kernel.org
Reported-by: Zheng Zhang <zheng.zhang@email.ucr.edu>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-ioctl.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 50a1259294d1..7d5c9c582ed2 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1556,11 +1556,12 @@ static int table_clear(struct file *filp, struct dm_ioctl *param, size_t param_s has_new_map = true; } - param->flags &= ~DM_INACTIVE_PRESENT_FLAG; - - __dev_status(hc->md, param); md = hc->md; up_write(&_hash_lock); + + param->flags &= ~DM_INACTIVE_PRESENT_FLAG; + __dev_status(md, param); + if (old_map) { dm_sync_table(md); dm_table_destroy(old_map); |