From: Miklos Szeredi <mszeredi@redhat.com>
Date: Fri, 28 Sep 2018 14:43:22 +0000 (+0200)
Subject: fuse: set FR_SENT while locked
X-Git-Tag: v4.18.20~124
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1b8ca12ee8afb4907b6b0a4b49e651c345f28aab;p=thirdparty%2Fkernel%2Fstable.git

fuse: set FR_SENT while locked

commit 4c316f2f3ff315cb48efb7435621e5bfb81df96d upstream.

Otherwise fuse_dev_do_write() could come in and finish off the request, and
the set_bit(FR_SENT, ...) could trigger the WARN_ON(test_bit(FR_SENT, ...))
in request_end().

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reported-by: syzbot+ef054c4d3f64cd7f7cec@syzkaller.appspotmai
Fixes: 46c34a348b0a ("fuse: no fc->lock for pqueue parts")
Cc: <stable@vger.kernel.org> # v4.2
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index aaa82849ace56..6be41a210b4de 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1319,8 +1319,8 @@ static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file,
 	}
 	list_move_tail(&req->list, &fpq->processing);
 	__fuse_get_request(req);
-	spin_unlock(&fpq->lock);
 	set_bit(FR_SENT, &req->flags);
+	spin_unlock(&fpq->lock);
 	/* matches barrier in request_wait_answer() */
 	smp_mb__after_atomic();
 	if (test_bit(FR_INTERRUPTED, &req->flags))