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

commit 8cb68751c115d176ec851ca56ecfbb411568c9e8 upstream.

If an invalid CAN 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+4386709c0c1284dca827@syzkaller.appspotmail.com
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
[bwh: Backported to 3.2:
 - Keep using the 'drop' label, as it has another user
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/can/af_can.c b/net/can/af_can.c
index 3ddc749..57c4364 100644 (file)
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -653,13 +653,13 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev,
        if (!net_eq(dev_net(dev), &init_net))
                goto drop;
 
-       if (WARN_ONCE(dev->type != ARPHRD_CAN ||
-                     skb->len != sizeof(struct can_frame) ||
-                     cf->can_dlc > 8,
-                     "PF_CAN: dropped non conform skbuf: "
-                     "dev type %d, len %d, can_dlc %d\n",
-                     dev->type, skb->len, cf->can_dlc))
+       if (unlikely(dev->type != ARPHRD_CAN ||
+                    skb->len != sizeof(struct can_frame) ||
+                    cf->can_dlc > 8)) {
+               pr_warn_once("PF_CAN: dropped non conform CAN skbuf: dev type %d, len %d, can_dlc %d\n",
+                            dev->type, skb->len, cf->can_dlc);
                goto drop;
+       }
 
        /* update statistics */
        can_stats.rx_frames++;