Re: [PATCH v2 net 2/4] bridge: check llc_mac_hdr_init() return value in br_send_bpdu()

[Nikolay Aleksandrov <razor@blackwall.org>]

On 24/09/2026 11:29, Eric Dumazet wrote:
> If llc_mac_hdr_init() fails (for instance if the port device type does
> not support LLC or dev_hard_header() fails), br_send_bpdu() should drop
> the skb instead of resetting the mac header to the LLC payload and
> transmitting a malformed frame.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Closes: https://lore.kernel.org/netdev/179022851638.2160803.1808206741379444999@kernel.org/
> Cc: Nikolay Aleksandrov <razor@blackwall.org>
> Cc: Ido Schimmel <idosch@nvidia.com>
> Cc: bridge@lists.linux.dev
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---
>   net/bridge/br_stp_bpdu.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_stp_bpdu.c b/net/bridge/br_stp_bpdu.c
> index 74ec42ba1e7d086cbfde608c93f5fa24d6b4ed7b..21d092f5acbb81f1d0ccd80200cebdbda722f4bf 100644
> --- a/net/bridge/br_stp_bpdu.c
> +++ b/net/bridge/br_stp_bpdu.c
> @@ -52,7 +52,10 @@ static void br_send_bpdu(struct net_bridge_port *p,
>   			    LLC_SAP_BSPAN, LLC_PDU_CMD);
>   	llc_pdu_init_as_ui_cmd(skb);
>   
> -	llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr);
> +	if (llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr)) {
> +		kfree_skb(skb);
> +		return;
> +	}
>   
>   	skb_reset_mac_header(skb);
>   

Acked-by: Nikolay Aleksandrov <razor@blackwall.org>