[PATCH 4.4 14/86] can: dev: __can_get_echo_skb(): Dont crash the kernel if can_priv::echo_skb is accessed out of bounds

Greg Kroah-Hartman
2018-11-29T14:17:12Z

From: Marc Kleine-Budde <mkl@pengutronix.de>

commit e7a6994d043a1e31d5b17706a22ce33d2a3e4cdc upstream.

If the "struct can_priv::echo_skb" is accessed out of bounds would lead
to a kernel crash. Better print a sensible warning message instead and
try to recover.

Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/can/dev.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -427,7 +427,11 @@ struct sk_buff *__can_get_echo_skb(struc
{
struct can_priv *priv = netdev_priv(dev);

- BUG_ON(idx >= priv->echo_skb_max);
+ if (idx >= priv->echo_skb_max) {
+ netdev_err(dev, "%s: BUG! Trying to access can_priv::echo_skb out of bounds (%u/max %u)\n",
+ __func__, idx, priv->echo_skb_max);
+ return NULL;
+ }

if (priv->echo_skb[idx]) {
/* Using "struct canfd_frame::len" for the frame