linux-kernel - [PATCH 13/18] virtiofs: Do not access virtqueue in request submission path

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Date:   Thu,  5 Sep 2019 15:48:54 -0400
From:   Vivek Goyal <vgoyal@...hat.com>
To:     linux-fsdevel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, miklos@...redi.hu
Cc:     linux-kernel@...r.kernel.org, virtio-fs@...hat.com,
        vgoyal@...hat.com, stefanha@...hat.com, dgilbert@...hat.com,
        mst@...hat.com
Subject: [PATCH 13/18] virtiofs: Do not access virtqueue in request submission path

In request submission path it is possible that virtqueue is already gone
due to driver->remove(). So do not access it in dev_dbg(). Use pr_debug()
instead.

If virtuqueue is gone, this will result in NULL pointer deference.

Signed-off-by: Vivek Goyal <vgoyal@...hat.com>
---
 fs/fuse/virtio_fs.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 40259368a6bd..01bbf2c0e144 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -888,10 +888,10 @@ __releases(fiq->waitq.lock)
 	fs = fiq->priv;
 	fc = fs->vqs[queue_id].fud->fc;
 
-	dev_dbg(&fs->vqs[queue_id].vq->vdev->dev,
-		"%s: opcode %u unique %#llx nodeid %#llx in.len %u out.len %u\n",
-		__func__, req->in.h.opcode, req->in.h.unique, req->in.h.nodeid,
-		req->in.h.len, fuse_len_args(req->out.numargs, req->out.args));
+	pr_debug("%s: opcode %u unique %#llx nodeid %#llx in.len %u out.len %u"
+		 "\n", __func__, req->in.h.opcode, req->in.h.unique,
+		 req->in.h.nodeid, req->in.h.len,
+		 fuse_len_args(req->out.numargs, req->out.args));
 
 	fpq = &fs->vqs[queue_id].fud->pq;
 	spin_lock(&fpq->lock);
-- 
2.20.1