[PATCH 6.6 113/603] can: dev: can_put_echo_skb(): dont crash kernel if can_priv::echo_skb is accessed out of bounds

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

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

[ Upstream commit 6411959c10fe917288cbb1038886999148560057 ]

If the "struct can_priv::echoo_skb" is accessed out of bounds, this
would cause a kernel crash. Instead, issue a meaningful warning
message and return with an error.

Fixes: a6e4bc530403 ("can: make the number of echo skb's configurable")
Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-5-91b5c1fd922c@pengutronix.de
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/can/dev/skb.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/dev/skb.c b/drivers/net/can/dev/skb.c
index f6d05b3ef59ab..3ebd4f779b9bd 100644
--- a/drivers/net/can/dev/skb.c
+++ b/drivers/net/can/dev/skb.c
@@ -49,7 +49,11 @@ int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
 {
 	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 -EINVAL;
+	}
 
 	/* check flag whether this packet has to be looped back */
 	if (!(dev->flags & IFF_ECHO) ||
-- 
2.42.0