[PATCH] vhost: fix virtqueue access lock check for handlers

[Maxime Coquelin]

On 3/7/24 11:36, David Marchand wrote:
> As the vhost library may receive a request for an unsupported request,
> it is necessary to check msg_handler before checking if locking queue
> pairs is requested.
> 
> Coverity issue: 415049
> Fixes: 5e8fcc60b59d ("vhost: enhance virtqueue access lock asserts")
> 
> Signed-off-by: David Marchand <david.marchand at redhat.com>
> ---
>   lib/vhost/vhost_user.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
> index 7fe1687f08..414192500e 100644
> --- a/lib/vhost/vhost_user.c
> +++ b/lib/vhost/vhost_user.c
> @@ -3171,7 +3171,7 @@ vhost_user_msg_handler(int vid, int fd)
>   	 * inactive, so it is safe. Otherwise taking the access_lock
>   	 * would cause a dead lock.
>   	 */
> -	if (msg_handler->lock_all_qps) {
> +	if (msg_handler != NULL && msg_handler->lock_all_qps) {
>   		if (!(dev->flags & VIRTIO_DEV_VDPA_CONFIGURED)) {
>   			vhost_user_lock_all_queue_pairs(dev);
>   			unlock_required = 1;

Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>

Thanks,
Maxime