From 065990bd198e0e67417c2c34e5e80140d4b8cef7 Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Mon, 23 Jul 2018 08:37:51 -0600 Subject: [PATCH] scsi: set timed out out mq requests to complete The scsi block layer requires requests claimed by the error handling be completed by the error handler. A previous commit allowed completions to proceed for blk-mq, breaking that assumption. This patch prevents completions that may race with the timeout handler by marking the state to complete, restoring the previous behavior. Fixes: 12f5b931 ("blk-mq: Remove generation seqeunce") Reviewed-by: Christoph Hellwig Signed-off-by: Keith Busch Signed-off-by: Jens Axboe --- drivers/scsi/scsi_error.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index 8932ae81a15a..2715cdaa669c 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -296,6 +296,20 @@ enum blk_eh_timer_return scsi_times_out(struct request *req) rtn = host->hostt->eh_timed_out(scmd); if (rtn == BLK_EH_DONE) { + /* + * For blk-mq, we must set the request state to complete now + * before sending the request to the scsi error handler. This + * will prevent a use-after-free in the event the LLD manages + * to complete the request before the error handler finishes + * processing this timed out request. + * + * If the request was already completed, then the LLD beat the + * time out handler from transferring the request to the scsi + * error handler. In that case we can return immediately as no + * further action is required. + */ + if (req->q->mq_ops && !blk_mq_mark_complete(req)) + return rtn; if (scsi_abort_command(scmd) != SUCCESS) { set_host_byte(scmd, DID_TIME_OUT); scsi_eh_scmd_add(scmd);