vhost-net: fix vq_memory_access_ok error checking

vq_memory_access_ok needs to check whether mem == NULL

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 7bd7a1e4409d..b8e112720812 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -235,6 +235,10 @@ static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
                                int log_all)
 {
         int i;
+
+        if (!mem)
+                return 0;
+
         for (i = 0; i < mem->nregions; ++i) {
                 struct vhost_memory_region *m = mem->regions + i;
                 unsigned long a = m->userspace_addr;