scsi: ufs: mcq: Add NULL check in ufshcd_mcq_abort()

A race can occur between the MCQ completion path and the abort handler:
once a request completes, __blk_mq_free_request() sets rq->mq_hctx to
NULL, meaning the subsequent ufshcd_mcq_req_to_hwq() call in
ufshcd_mcq_abort() can return a NULL pointer. If this NULL pointer is
dereferenced, the kernel will crash.

Add a NULL check for the returned hwq pointer. If hwq is NULL, log an
error and return FAILED, preventing a potential NULL-pointer
dereference.  As suggested by Bart, the ufshcd_cmd_inflight() check is
removed.

This is similar to the fix in commit 7473610 ("scsi: ufs: core: Fix
ufshcd_abort_one racing issue").

This is found by our static analysis tool KNighter.

Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
Link: https://lore.kernel.org/r/20250410001320.2219341-1-chenyuan0y@gmail.com
Fixes: f1304d4 ("scsi: ufs: mcq: Added ufshcd_mcq_abort()")
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/ufs/core/ufs-mcq.c

@@ -677,13 +677,6 @@ int ufshcd_mcq_abort(struct scsi_cmnd *cmd)
 	unsigned long flags;
 	int err;
 
-	if (!ufshcd_cmd_inflight(lrbp->cmd)) {
-		dev_err(hba->dev,
-			"%s: skip abort. cmd at tag %d already completed.\n",
-			__func__, tag);
-		return FAILED;
-	}
-
 	/* Skip task abort in case previous aborts failed and report failure */
 	if (lrbp->req_abort_skip) {
 		dev_err(hba->dev, "%s: skip abort. tag %d failed earlier\n",
@@ -692,6 +685,11 @@ int ufshcd_mcq_abort(struct scsi_cmnd *cmd)
 	}
 
 	hwq = ufshcd_mcq_req_to_hwq(hba, scsi_cmd_to_rq(cmd));
+	if (!hwq) {
+		dev_err(hba->dev, "%s: skip abort. cmd at tag %d already completed.\n",
+			__func__, tag);
+		return FAILED;
+	}
 
 	if (ufshcd_mcq_sqe_search(hba, hwq, tag)) {
 		/*