AFS: Potential null dereference

It seems clear from the surrounding code that xpermits is allowed to be
NULL here.
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/afs/security.c

@@ -189,6 +189,7 @@ void afs_cache_permit(struct afs_vnode *vnode, struct key *key, long acl_order)
 	if (!permits)
 		goto out_unlock;
 
+	if (xpermits)
 		memcpy(permits->permits, xpermits->permits,
 			count * sizeof(struct afs_permit));