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nbd: fix race between timeout and normal completion

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If request timetout is handled by nbd_requeue_cmd(), normal completion
has to be stopped for avoiding to complete this requeued request, other
use-after-free can be triggered.

Fix the race by clearing NBD_CMD_INFLIGHT in nbd_requeue_cmd(), meantime
make sure that cmd->lock is grabbed for clearing the flag and the
requeue.

Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Fixes: 2895f1831e ("nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240830034145.1827742-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2024-08-30 11:41:45 +08:00 committed by Jens Axboe
parent 12c612e115
commit c9ea57c91f
1 changed files with 12 additions and 1 deletions
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13
drivers/block/nbd.c
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@ -181,6 +181,17 @@ static void nbd_requeue_cmd(struct nbd_cmd *cmd)
{
struct request *req = blk_mq_rq_from_pdu(cmd);
lockdep_assert_held(&cmd->lock);
/*
* Clear INFLIGHT flag so that this cmd won't be completed in
* normal completion path
*
* INFLIGHT flag will be set when the cmd is queued to nbd next
* time.
*/
__clear_bit(NBD_CMD_INFLIGHT, &cmd->flags);
if (!test_and_set_bit(NBD_CMD_REQUEUED, &cmd->flags))
blk_mq_requeue_request(req, true);
}
@ -491,8 +502,8 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req)
nbd_mark_nsock_dead(nbd, nsock, 1);
mutex_unlock(&nsock->tx_lock);
}
mutex_unlock(&cmd->lock);
nbd_requeue_cmd(cmd);
mutex_unlock(&cmd->lock);
nbd_config_put(nbd);
return BLK_EH_DONE;
}