This is a note to let you know that I've just added the patch titled can: isotp: tx-path: zero initialize outgoing CAN frames to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: can-isotp-tx-path-zero-initialize-outgoing-can-frame.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit fba5b9f911327b6c1594d7f8492817012b34b27f Author: Oliver Hartkopp <socketcan@xxxxxxxxxxxx> Date: Fri Mar 19 11:06:19 2021 +0100 can: isotp: tx-path: zero initialize outgoing CAN frames [ Upstream commit b5f020f82a8e41201c6ede20fa00389d6980b223 ] Commit d4eb538e1f48 ("can: isotp: TX-path: ensure that CAN frame flags are initialized") ensured the TX flags to be properly set for outgoing CAN frames. In fact the root cause of the issue results from a missing initialization of outgoing CAN frames created by isotp. This is no problem on the CAN bus as the CAN driver only picks the correctly defined content from the struct can(fd)_frame. But when the outgoing frames are monitored (e.g. with candump) we potentially leak some bytes in the unused content of struct can(fd)_frame. Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol") Cc: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20210319100619.10858-1-socketcan@xxxxxxxxxxxx Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx> Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/can/isotp.c b/net/can/isotp.c index 430976485d95..15ea1234d457 100644 --- a/net/can/isotp.c +++ b/net/can/isotp.c @@ -196,7 +196,7 @@ static int isotp_send_fc(struct sock *sk, int ae, u8 flowstatus) nskb->dev = dev; can_skb_set_owner(nskb, sk); ncf = (struct canfd_frame *)nskb->data; - skb_put(nskb, so->ll.mtu); + skb_put_zero(nskb, so->ll.mtu); /* create & send flow control reply */ ncf->can_id = so->txid; @@ -779,7 +779,7 @@ isotp_tx_burst: can_skb_prv(skb)->skbcnt = 0; cf = (struct canfd_frame *)skb->data; - skb_put(skb, so->ll.mtu); + skb_put_zero(skb, so->ll.mtu); /* create consecutive frame */ isotp_fill_dataframe(cf, so, ae, 0); @@ -895,7 +895,7 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) so->tx.idx = 0; cf = (struct canfd_frame *)skb->data; - skb_put(skb, so->ll.mtu); + skb_put_zero(skb, so->ll.mtu); /* check for single frame transmission depending on TX_DL */ if (size <= so->tx.ll_dl - SF_PCI_SZ4 - ae - off) {