[PATCH 4.19 029/321] can: rx-offload: can_rx_offload_offload_one(): do not increase the skb_queue beyond skb_queue_len_max

Greg Kroah-Hartman
2019-12-03T23:08:02Z

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

[ Upstream commit a2dc3f5e1022a5ede8af9ab89a144f1e69db8636 ]

The skb_queue is a linked list, holding the skb to be processed in the
next NAPI call.

Without this patch, the queue length in can_rx_offload_offload_one() is
limited to skb_queue_len_max + 1. As the skb_queue is a linked list, no
array or other resources are accessed out-of-bound, however this
behaviour is counterintuitive.

This patch limits the rx-offload skb_queue length to skb_queue_len_max.

Fixes: d254586c3453 ("can: rx-offload: Add support for HW fifo based irq offloading")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/can/rx-offload.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/rx-offload.c b/drivers/net/can/rx-offload.c
index a90005eac8b17..e32b65599a5f2 100644
--- a/drivers/net/can/rx-offload.c
+++ b/drivers/net/can/rx-offload.c
@@ -124,7 +124,7 @@ static struct sk_buff *can_rx_offload_offload_one(struct can_rx_offload *offload
int ret;

/* If queue is full or skb not available, read to discard mailbox */
- if (likely(skb_queue_len(&offload->skb_queue) <=
+ if (likely(skb_queue_len(&offload->skb_queue) <
offload->skb_queue_len_max))
skb = alloc_can_skb(offload->dev, &cf);

--
2.20.1