On Tue, Mar 15, 2022 at 09:48:52AM +0100, Hans Schultz wrote:

On mån, mar 14, 2022 at 17:30, Ido Schimmel [off-list ref] wrote:

quoted

On Thu, Mar 10, 2022 at 03:23:18PM +0100, Hans Schultz wrote:

quoted

@@ -94,8 +95,16 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
 			br_fdb_find_rcu(br, eth_hdr(skb)->h_source, vid);
 
 		if (!fdb_src || READ_ONCE(fdb_src->dst) != p ||
-		    test_bit(BR_FDB_LOCAL, &fdb_src->flags))
+		    test_bit(BR_FDB_LOCAL, &fdb_src->flags)) {
+			if (!fdb_src) {
+				set_bit(BR_FDB_ENTRY_LOCKED, &flags);

This flag is read-only for user space, right? That is, the kernel needs
to reject it during netlink policy validation.

Yes, the flag is only readable from user space, unless there is a wish
to change that.

OK, so please spell it out in the commit message so that it is clear the
flag can only be set by the kernel.