From: Miklos Szeredi <mszeredi@redhat.com>
Date: Mon, 21 Oct 2019 09:11:40 +0200
Subject: fuse: don't dereference req->args on finished request
Git-commit: 2b319d1f6f92a4ced9897678113d176ee16ae85d
Patch-mainline: v5.4-rc6
References: jsc#SLE-13782

Move the check for async request after check for the request being already
finished and done with.

Reported-by: syzbot+ae0bb7aae3de6b4594e2@syzkaller.appspotmail.com
Fixes: d49937749fef ("fuse: stop copying args to fuse_req")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Acked-by: Luis Henriques <lhenriques@suse.com>
---
 fs/fuse/dev.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index dadd617d826c..ed1abc9e33cf 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -276,10 +276,12 @@ static void flush_bg_queue(struct fuse_conn *fc)
 void fuse_request_end(struct fuse_conn *fc, struct fuse_req *req)
 {
 	struct fuse_iqueue *fiq = &fc->iq;
-	bool async = req->args->end;
+	bool async;
 
 	if (test_and_set_bit(FR_FINISHED, &req->flags))
 		goto put_request;
+
+	async = req->args->end;
 	/*
 	 * test_and_set_bit() implies smp_mb() between bit
 	 * changing and below intr_entry check. Pairs with