genetlink: Fix a memory leak on error path

In genl_register_family(), when idr_alloc() fails,
we forget to free the memory we possibly allocate for
family->attrbuf.
Reported-by: NHulk Robot <hulkci@huawei.com>
Fixes: 2ae0f17d ("genetlink: use idr to track families")
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Reviewed-by: NKirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/netlink/genetlink.c

@@ -366,7 +366,7 @@ int genl_register_family(struct genl_family *family)
 			       start, end + 1, GFP_KERNEL);
 	if (family->id < 0) {
 		err = family->id;
-		goto errout_locked;
+		goto errout_free;
 	}
 
 	err = genl_validate_assign_mc_groups(family);
@@ -385,6 +385,7 @@ int genl_register_family(struct genl_family *family)
 
 errout_remove:
 	idr_remove(&genl_fam_idr, family->id);
+errout_free:
 	kfree(family->attrbuf);
 errout_locked:
 	genl_unlock_all();