dm thin metadata: check fail_io before using data_sm
Must check pmd->fail_io before using pmd->data_sm since
pmd->data_sm may be destroyed by other processes.
P1(kworker) P2(message)
do_worker
process_prepared
process_prepared_discard_passdown_pt2
dm_pool_dec_data_range
pool_message
commit
dm_pool_commit_metadata
↓
// commit failed
metadata_operation_failed
abort_transaction
dm_pool_abort_metadata
__open_or_format_metadata
↓
dm_sm_disk_open
↓
// open failed
// pmd->data_sm is NULL
dm_sm_dec_blocks
↓
// try to access pmd->data_sm --> UAF
As shown above, if dm_pool_commit_metadata() and
dm_pool_abort_metadata() fail in pool_message process, kworker may
trigger UAF.
Fixes:
be500ed721a6 ("dm space maps: improve performance with inc/dec on ranges of blocks")
Cc: stable@vger.kernel.org
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>