NVMe: fix race condition in nvme_submit_sync_cmd()
If we have a race between the schedule timing out and the command
completing, we could have the task issuing the command exit
nvme_submit_sync_cmd() while the irq is running sync_completion().
If that happens, we could be corrupting memory, since the stack
that held 'cmdinfo' is no longer valid.
Fix this by always calling nvme_abort_cmd_info(). Once that call
completes, we know that we have either run sync_completion() if
the completion came in, or that we will never run it since we now
have special_completion() as the command callback handler.
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index e92bdf4c..b1d5d87 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -804,12 +804,19 @@
nvme_finish_cmd(nvmeq, req->tag, NULL);
set_current_state(TASK_RUNNING);
}
- schedule_timeout(timeout);
+ ret = schedule_timeout(timeout);
- if (cmdinfo.status == -EINTR) {
- nvme_abort_cmd_info(nvmeq, blk_mq_rq_to_pdu(req));
+ /*
+ * Ensure that sync_completion has either run, or that it will
+ * never run.
+ */
+ nvme_abort_cmd_info(nvmeq, blk_mq_rq_to_pdu(req));
+
+ /*
+ * We never got the completion
+ */
+ if (cmdinfo.status == -EINTR)
return -EINTR;
- }
if (result)
*result = cmdinfo.result;