From ac704ff08e511c87643799c385f55ecd69b85e03 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 24 Sep 2026 08:29:49 +0000 Subject: [PATCH] bridge: check llc_mac_hdr_init() return value in br_send_bpdu() 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 Cc: Ido Schimmel Cc: bridge@lists.linux.dev Signed-off-by: Eric Dumazet Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20260924082951.1599377-3-edumazet@google.com Signed-off-by: Jakub Kicinski --- 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 74ec42ba1e7d..21d092f5acbb 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);