From: Qendrim Maxhuni <qendrim.maxhuni@garderos.com> [ Upstream commit e120f46768d98151ece8756ebd688b0e43dc8b29 ] Raw IP packets have no MAC header, leaving skb->mac_header uninitialized. This can trigger kernel panics on ARM64 when xfrm or other subsystems access the offset due to strict alignment checks. Initialize the MAC header to prevent such crashes. This can trigger kernel panics on ARM when running IPsec over the qmimux0 interface. Example trace: Internal error: Oops: 000000009600004f [#1] SMP CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.12.34-gbe78e49cb433 #1 Hardware name: LS1028A RDB Board (DT) pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : xfrm_input+0xde8/0x1318 lr : xfrm_input+0x61c/0x1318 sp : ffff800080003b20 Call trace: xfrm_input+0xde8/0x1318 xfrm6_rcv+0x38/0x44 xfrm6_esp_rcv+0x48/0xa8 ip6_protocol_deliver_rcu+0x94/0x4b0 ip6_input_finish+0x44/0x70 ip6_input+0x44/0xc0 ipv6_rcv+0x6c/0x114 __netif_receive_skb_one_core+0x5c/0x8c __netif_receive_skb+0x18/0x60 process_backlog+0x78/0x17c __napi_poll+0x38/0x180 net_rx_action+0x168/0x2f0 Fixes: c6adf77953bc ("net: usb: qmi_wwan: add qmap mux protocol support") Signed-off-by: Qendrim Maxhuni <qendrim.maxhuni@garderos.com> Link: https://patch.msgid.link/20251029075744.105113-1-qendrim.maxhuni@garderos.co... Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> --- drivers/net/usb/qmi_wwan.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c index eba755b584a4..73df808978b2 100644 --- a/drivers/net/usb/qmi_wwan.c +++ b/drivers/net/usb/qmi_wwan.c @@ -192,6 +192,12 @@ static int qmimux_rx_fixup(struct usbnet *dev, struct sk_buff *skb) if (!skbn) return 0; + /* Raw IP packets don't have a MAC header, but other subsystems + * (like xfrm) may still access MAC header offsets, so they must + * be initialized. + */ + skb_reset_mac_header(skbn); + switch (skb->data[offset + qmimux_hdr_sz] & 0xf0) { case 0x40: skbn->protocol = htons(ETH_P_IP); -- 2.43.0