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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Miklos Szeredi <mszeredi@redhat.com>
Subject: [PATCH 4.14 120/165] fuse: fix double request_end()
Date:   Mon,  3 Sep 2018 18:56:46 +0200
Message-Id: <20180903165701.555598735@linuxfoundation.org>
In-Reply-To: <20180903165655.003605184@linuxfoundation.org>
References: <20180903165655.003605184@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Miklos Szeredi <mszeredi@redhat.com>

commit 87114373ea507895a62afb10d2910bd9adac35a8 upstream.

Refcounting of request is broken when fuse_abort_conn() is called and
request is on the fpq->io list:

 - ref is taken too late
 - then it is not dropped

Fixes: 0d8e84b0432b ("fuse: simplify request abort")
Cc: <stable@vger.kernel.org> # v4.2
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/fuse/dev.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -364,7 +364,7 @@ static void request_end(struct fuse_conn
 	struct fuse_iqueue *fiq = &fc->iq;
 
 	if (test_and_set_bit(FR_FINISHED, &req->flags))
-		return;
+		goto out_put_req;
 
 	spin_lock(&fiq->waitq.lock);
 	list_del_init(&req->intr_entry);
@@ -393,6 +393,7 @@ static void request_end(struct fuse_conn
 	wake_up(&req->waitq);
 	if (req->end)
 		req->end(fc, req);
+out_put_req:
 	fuse_put_request(fc, req);
 }
 
@@ -2103,6 +2104,7 @@ void fuse_abort_conn(struct fuse_conn *f
 				set_bit(FR_ABORTED, &req->flags);
 				if (!test_bit(FR_LOCKED, &req->flags)) {
 					set_bit(FR_PRIVATE, &req->flags);
+					__fuse_get_request(req);
 					list_move(&req->list, &to_end1);
 				}
 				spin_unlock(&req->waitq.lock);
@@ -2129,7 +2131,6 @@ void fuse_abort_conn(struct fuse_conn *f
 
 		while (!list_empty(&to_end1)) {
 			req = list_first_entry(&to_end1, struct fuse_req, list);
-			__fuse_get_request(req);
 			list_del_init(&req->list);
 			request_end(fc, req);
 		}