FAILED: patch "[PATCH] nvmet: fix a use-after-free" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Possible dependencies:

6a02a61e81c2 ("nvmet: fix a use-after-free")
a5448fdc469d ("nvmet: introduce target-side trace")
76574f37bf4c ("nvmet: add interface to update error-log page") 872d26a391da ("nvmet-tcp: add NVMe over TCP target driver") cb019da3dabf ("nvmet: use unlikely for req status check") e6a622fd6d66 ("nvmet: support fabrics sq flow control") 55eb942eda2c ("nvmet: add buffered I/O support for file backed ns") d5eff33ee6f8 ("nvmet: add simple file backed ns support") 618cff4285dc ("nvmet: remove duplicate NULL initialization for req->ns") e929f06d9eaa ("nvmet: constify struct nvmet_fabrics_ops") 4c6526858810 ("nvmet: don't return "any" ip address in discovery log page") 423b4487fb23 ("nvmet: release a ns reference in nvmet_req_uninit if needed")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6a02a61e81c231cc5c680c5dbf8665275147ac52 Mon Sep 17 00:00:00 2001
From: Bart Van Assche <[email protected]>
Date: Fri, 12 Aug 2022 14:03:17 -0700
Subject: [PATCH] nvmet: fix a use-after-free

Fix the following use-after-free complaint triggered by blktests nvme/004:

BUG: KASAN: user-memory-access in blk_mq_complete_request_remote+0xac/0x350
Read of size 4 at addr 0000607bd1835943 by task kworker/13:1/460
Workqueue: nvmet-wq nvme_loop_execute_work [nvme_loop]
Call Trace:
 show_stack+0x52/0x58
 dump_stack_lvl+0x49/0x5e
 print_report.cold+0x36/0x1e2
 kasan_report+0xb9/0xf0
 __asan_load4+0x6b/0x80
 blk_mq_complete_request_remote+0xac/0x350
 nvme_loop_queue_response+0x1df/0x275 [nvme_loop]
 __nvmet_req_complete+0x132/0x4f0 [nvmet]
 nvmet_req_complete+0x15/0x40 [nvmet]
 nvmet_execute_io_connect+0x18a/0x1f0 [nvmet]
 nvme_loop_execute_work+0x20/0x30 [nvme_loop]
 process_one_work+0x56e/0xa70
 worker_thread+0x2d1/0x640
 kthread+0x183/0x1c0
 ret_from_fork+0x1f/0x30

index a1345790005f..7f4083cf953a 100644
@@ -735,6 +735,8 @@ static void nvmet_set_error(struct nvmet_req *req, u16 status)
 
 static void __nvmet_req_complete(struct nvmet_req *req, u16 status)
 {
+	struct nvmet_ns *ns = req->ns;
+
 	if (!req->sq->sqhd_disabled)
 		nvmet_update_sq_head(req);
 	req->cqe->sq_id = cpu_to_le16(req->sq->qid);

@@ -745,9 +747,9 @@ static void __nvmet_req_complete(struct nvmet_req *req, u16 status)
 
 	trace_nvmet_req_complete(req);
 
-	if (req->ns)
-		nvmet_put_namespace(req->ns);
 	req->ops->queue_response(req);
+	if (ns)
+		nvmet_put_namespace(ns);
 }
 
 void nvmet_req_complete(struct nvmet_req *req, u16 status)