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| author | Mike Snitzer <snitzer@kernel.org> | 2023-04-17 11:59:56 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-17 11:13:21 +0200 |
| commit | b4b94b25c78ed03be0e07fa4e76fe51e64dac533 (patch) | |
| tree | 4fbfad2a2a13d82c899ab6f52bb8ae4cba21faf6 | |
| parent | 12849ed107c0b2869fb775c81208050899006f07 (diff) | |
| download | linux-stable-b4b94b25c78ed03be0e07fa4e76fe51e64dac533.tar.gz linux-stable-b4b94b25c78ed03be0e07fa4e76fe51e64dac533.tar.bz2 linux-stable-b4b94b25c78ed03be0e07fa4e76fe51e64dac533.zip | |
dm ioctl: fix nested locking in table_clear() to remove deadlock concern
commit 3d32aaa7e66d5c1479a3c31d6c2c5d45dd0d3b89 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 0c8ddf37ef39..e1603c17e346 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1410,11 +1410,12 @@ static int table_clear(struct file *filp, struct dm_ioctl *param, size_t param_s hc->new_map = NULL; } - 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); |