can: can327: can327_feed_frame_to_netdev(): fix potential skb leak when netdev is down

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2071839
Tested: This is one of a series of patch sets to enable Arm SystemReady IR
 support.  This set updates the CAN driver subsystem.  This set has
 been tested on NXP imx8mm and NV Jetson Xavier NX via simple boot
 tests, using cansend/candump from can-utils to pass messages through
 a virtual CAN interface, and of course the CI loop.

commit 8fa452c
Author: Ziyang Xuan <william.xuanziyang@huawei.com>
Date:   Thu Nov 10 14:14:37 2022 +0800

    can: can327: can327_feed_frame_to_netdev(): fix potential skb leak when netdev is down

    In can327_feed_frame_to_netdev(), it did not free the skb when netdev
    is down, and all callers of can327_feed_frame_to_netdev() did not free
    allocated skb too. That would trigger skb leak.

    Fix it by adding kfree_skb() in can327_feed_frame_to_netdev() when netdev
    is down. Not tested, just compiled.

    Fixes: 43da2f0 ("can: can327: CAN/ldisc driver for ELM327 based OBD-II adapters")
    Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
    Link: https://lore.kernel.org/all/20221110061437.411525-1-william.xuanziyang@huawei.com
    Reviewed-by: Max Staudt <max@enpas.org>
    Cc: stable@vger.kernel.org
    Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
    (cherry picked from commit 8fa452c)

Signed-off-by: Al Stone <ahs3@redhat.com>

Author: Al Stone

drivers/net/can/can327.c

@@ -263,8 +263,10 @@ static void can327_feed_frame_to_netdev(struct can327 *elm, struct sk_buff *skb)
 {
 	lockdep_assert_held(&elm->lock);
 
-	if (!netif_running(elm->dev))
+	if (!netif_running(elm->dev)) {
+		kfree_skb(skb);
 		return;
+	}
 
 	/* Queue for NAPI pickup.
 	 * rx-offload will update stats and LEDs for us.