NFSv4/pnfs: Fix a use-after-free bug in open

jira LE-3201
Rebuild_History Non-Buildable kernel-rt-4.18.0-553.22.1.rt7.363.el8_10
commit-author Trond Myklebust <trond.myklebust@hammerspace.com>
commit 2135e5d

If someone cancels the open RPC call, then we must not try to free
either the open slot or the layoutget operation arguments, since they
are likely still in use by the hung RPC call.

Fixes: 6949493 ("NFSv4: Don't hold the layoutget locks across multiple RPC calls")
	Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
(cherry picked from commit 2135e5d)
	Signed-off-by: Jonathan Maple <jmaple@ciq.com>

Author: PlaidCat

fs/nfs/nfs4proc.c

@@ -3117,12 +3117,13 @@ static int _nfs4_open_and_get_state(struct nfs4_opendata *opendata,
 	}
 
 out:
-	if (opendata->lgp) {
-		nfs4_lgopen_release(opendata->lgp);
-		opendata->lgp = NULL;
-	}
-	if (!opendata->cancelled)
+	if (!opendata->cancelled) {
+		if (opendata->lgp) {
+			nfs4_lgopen_release(opendata->lgp);
+			opendata->lgp = NULL;
+		}
 		nfs4_sequence_free_slot(&opendata->o_res.seq_res);
+	}
 	return ret;
 }