In Linux 4.12 commit 8e8cda6d737d356054c ("can: initial support for network namespaces") removed a namespace check which affected this patch:

can: af_can: canfd_rcv(): replace WARN_ONCE by pr_warn_once

upstream commit d4689846881d160a4d12a514e991a740bcb5d65a

If an invalid CANFD frame is received, from a driver or from a tun interface, a Kernel warning is generated.

This patch replaces the WARN_ONCE by a simple pr_warn_once, so that a kernel, bootet with panic_on_warn, does not panic. A printk seems to be more appropriate here.

Reported-by: syzbot+e3b775f40babeff6e68b@syzkaller.appspotmail.com Suggested-by: Dmitry Vyukov dvyukov@google.com Acked-by: Oliver Hartkopp socketcan@hartkopp.net Cc: linux-stable stable@vger.kernel.org [pre 4.12] Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de Signed-off-by: Oliver Hartkopp socketcan@hartkopp.net --- net/can/af_can.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/net/can/af_can.c b/net/can/af_can.c index 924ad0513af9..c866e761651a 100644 --- a/net/can/af_can.c +++ b/net/can/af_can.c @@ -745,13 +745,12 @@ static int canfd_rcv(struct sk_buff *skb, struct net_device *dev, if (unlikely(!net_eq(dev_net(dev), &init_net))) goto drop;

- if (WARN_ONCE(dev->type != ARPHRD_CAN || - skb->len != CANFD_MTU || - cfd->len > CANFD_MAX_DLEN, - "PF_CAN: dropped non conform CAN FD skbuf: " - "dev type %d, len %d, datalen %d\n", - dev->type, skb->len, cfd->len)) + if (unlikely(dev->type != ARPHRD_CAN || skb->len != CANFD_MTU || + cfd->len > CANFD_MAX_DLEN)) { + pr_warn_once("PF_CAN: dropped non conform CAN FD skbuf: dev type %d, len %d, datalen %d\n", + dev->type, skb->len, cfd->len); goto drop; + }

can_receive(skb, dev); return NET_RX_SUCCESS;