From: Miklos Szeredi <mszeredi@redhat.com>
Date: Thu, 26 Jul 2018 14:13:11 +0000 (+0200)
Subject: fuse: fix unlocked access to processing queue
X-Git-Tag: Ubuntu-4.15.0-49.53~84
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=1011a05d99d431041dd6a577c3812be700d18fe9;p=mirror_ubuntu-bionic-kernel.git

fuse: fix unlocked access to processing queue

BugLink: https://bugs.launchpad.net/bugs/1824553

fuse_dev_release() assumes that it's the only one referencing the
fpq->processing list, but that's not true, since fuse_abort_conn() can be
doing the same without any serialization between the two.

Fixes: c3696046beb3 ("fuse: separate pqueue for clones")
Cc: <stable@vger.kernel.org> # v4.2
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
(cherry picked from commit 45ff350bbd9d0f0977ff270a0d427c71520c0c37)
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
---

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index c973006eaf90..b28cbc0532ce 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -2155,9 +2155,15 @@ int fuse_dev_release(struct inode *inode, struct file *file)
 	if (fud) {
 		struct fuse_conn *fc = fud->fc;
 		struct fuse_pqueue *fpq = &fud->pq;
+		LIST_HEAD(to_end);
 
+		spin_lock(&fpq->lock);
 		WARN_ON(!list_empty(&fpq->io));
-		end_requests(fc, &fpq->processing);
+		list_splice_init(&fpq->processing, &to_end);
+		spin_unlock(&fpq->lock);
+
+		end_requests(fc, &to_end);
+
 		/* Are we the last open device? */
 		if (atomic_dec_and_test(&fc->dev_count)) {
 			WARN_ON(fc->iq.fasync != NULL);