vhost_vsock_stop() calls vhost_dev_check_owner() to check the device
ownership. It expects current->mm to be valid.
vhost_vsock_stop() is also called by vhost_vsock_dev_release() when
the user has not done close(), so when we are in do_exit(). In this
case current->mm is invalid and we're releasing the device, so we
should clean it anyway.
Let's check the owner only when vhost_vsock_stop() is called
by an ioctl.
When invoked from release we can not fail so we don't check return
code of vhost_vsock_stop(). We need to stop vsock even if it's not
the owner.
Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: syzbot+1e3ea63db39f2b4440e0@xxxxxxxxxxxxxxxxxxxxxxxxx
Reported-and-tested-by: syzbot+3140b17cb44a7b174008@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
---
v2:
- initialized `ret` in vhost_vsock_stop [Dan]
- added comment about vhost_vsock_stop() calling in the code and an explanation
in the commit message [MST]
v1: https://lore.kernel.org/virtualization/20220221114916.107045-1-sgarzare@xxxxxxxxxx
---
drivers/vhost/vsock.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index d6ca1c7ad513..37f0b4274113 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -629,16 +629,18 @@ static int vhost_vsock_start(struct vhost_vsock *vsock)
return ret;
}
-static int vhost_vsock_stop(struct vhost_vsock *vsock)
+static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner)
{
size_t i;
- int ret;
+ int ret = 0;
mutex_lock(&vsock->dev.mutex);
- ret = vhost_dev_check_owner(&vsock->dev);
- if (ret)
- goto err;
+ if (check_owner) {
+ ret = vhost_dev_check_owner(&vsock->dev);
+ if (ret)
+ goto err;
+ }
for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
struct vhost_virtqueue *vq = &vsock->vqs[i];
@@ -753,7 +755,12 @@ static int vhost_vsock_dev_release(struct inode *inode, struct file *file)
* inefficient. Room for improvement here. */
vsock_for_each_connected_socket(vhost_vsock_reset_orphans);
- vhost_vsock_stop(vsock);
+ /* Don't check the owner, because we are in the release path, so we
+ * need to stop the vsock device in any case.
+ * vhost_vsock_stop() can not fail in this case, so we don't need to
+ * check the return code.
+ */
+ vhost_vsock_stop(vsock, false);
vhost_vsock_flush(vsock);
vhost_dev_stop(&vsock->dev);
@@ -868,7 +875,7 @@ static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl,
if (start)
return vhost_vsock_start(vsock);
else
- return vhost_vsock_stop(vsock);
+ return vhost_vsock_stop(vsock, true);
case VHOST_GET_FEATURES:
features = VHOST_VSOCK_FEATURES;
if (copy_to_user(argp, &features, sizeof(features)))
--
2.35.1
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