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Commit 0b608b33 authored by Stefano Garzarella's avatar Stefano Garzarella Committed by Greg Kroah-Hartman
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vhost/vsock: don't check owner in vhost_vsock_stop() while releasing 



commit a58da53ffd70294ebea8ecd0eb45fd0d74add9f9 upstream.

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: 433fc58e ("VSOCK: Introduce vhost_vsock.ko")
Cc: stable@vger.kernel.org
Reported-by: default avatar <syzbot+1e3ea63db39f2b4440e0@syzkaller.appspotmail.com>
Reported-and-tested-by: default avatar <syzbot+3140b17cb44a7b174008@syzkaller.appspotmail.com>
Signed-off-by: default avatarStefano Garzarella <sgarzare@redhat.com>
Acked-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent dd0de351

drivers/vhost/vsock.c

+14 −7
Original line number Diff line number Diff line
@@ -570,16 +570,18 @@ 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);



	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];
@@ -694,7 +696,12 @@ 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);
@@ -792,7 +799,7 @@ 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)))