[PATCH stable] can: af_can: fix NULL pointer dereference in can_rcv_filter

[PATCH stable] can: af_can: fix NULL pointer dereference in can_rcv_filter

[Oliver Hartkopp]

Analogue to commit 8aa59e355949 ("can: af_can: fix NULL pointer
dereference in can_rx_register()") we need to check for a missing
initialization of ml_priv in the receive path of CAN frames.

Since commit 4e096a18867a ("net: introduce CAN specific pointer in the
struct net_device") the check for dev->type to be ARPHRD_CAN is not
sufficient anymore since bonding or tun netdevices claim to be CAN
devices but do not initialize ml_priv accordingly.

Upstream commit 0acc442309a0 ("can: af_can: fix NULL pointer
dereference in can_rcv_filter")

Fixes: 4e096a18867a ("net: introduce CAN specific pointer in the struct net_device")
Reported-by: syzbot+2d7f58292cb5b29eb5ad@syzkaller.appspotmail.com
Reported-by: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: stable@vger.kernel.org # 5.12 .. 6.0
---
 net/can/af_can.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/can/af_can.c b/net/can/af_can.c
index 1fb49d51b25d..4392f1d9c027 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -678,11 +678,11 @@ static void can_receive(struct sk_buff *skb, struct net_device *dev)
 static int can_rcv(struct sk_buff *skb, struct net_device *dev,
 		   struct packet_type *pt, struct net_device *orig_dev)
 {
 	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
 
-	if (unlikely(dev->type != ARPHRD_CAN || skb->len != CAN_MTU)) {
+	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || skb->len != CAN_MTU)) {
 		pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 		goto free_skb;
 	}
 
@@ -704,11 +704,11 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev,
 static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
 		     struct packet_type *pt, struct net_device *orig_dev)
 {
 	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
 
-	if (unlikely(dev->type != ARPHRD_CAN || skb->len != CANFD_MTU)) {
+	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || skb->len != CANFD_MTU)) {
 		pr_warn_once("PF_CAN: dropped non conform CAN FD skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 		goto free_skb;
 	}
 
-- 
2.30.2

Re: [PATCH stable] can: af_can: fix NULL pointer dereference in can_rcv_filter

[Oliver Hartkopp]

Just checked that the stable patch for 8aa59e355949 ("can: af_can: fix 
NULL pointer dereference in can_rx_register()") has been applied down to 
linux-5.4.y

Same works with this patch.

Just the current 6.1-rc has some changes in this section which makes 
this backport stable patch necessary.

Best,
Oliver


On 09.12.22 19:07, Oliver Hartkopp wrote:
> Analogue to commit 8aa59e355949 ("can: af_can: fix NULL pointer
> dereference in can_rx_register()") we need to check for a missing
> initialization of ml_priv in the receive path of CAN frames.
> 
> Since commit 4e096a18867a ("net: introduce CAN specific pointer in the
> struct net_device") the check for dev->type to be ARPHRD_CAN is not
> sufficient anymore since bonding or tun netdevices claim to be CAN
> devices but do not initialize ml_priv accordingly.
> 
> Upstream commit 0acc442309a0 ("can: af_can: fix NULL pointer
> dereference in can_rcv_filter")
> 
> Fixes: 4e096a18867a ("net: introduce CAN specific pointer in the struct net_device")
> Reported-by: syzbot+2d7f58292cb5b29eb5ad@syzkaller.appspotmail.com
> Reported-by: Wei Chen <harperchen1110@gmail.com>
> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
> Cc: stable@vger.kernel.org # 5.12 .. 6.0
> ---
>   net/can/af_can.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/can/af_can.c b/net/can/af_can.c
> index 1fb49d51b25d..4392f1d9c027 100644
> --- a/net/can/af_can.c
> +++ b/net/can/af_can.c
> @@ -678,11 +678,11 @@ static void can_receive(struct sk_buff *skb, struct net_device *dev)
>   static int can_rcv(struct sk_buff *skb, struct net_device *dev,
>   		   struct packet_type *pt, struct net_device *orig_dev)
>   {
>   	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
>   
> -	if (unlikely(dev->type != ARPHRD_CAN || skb->len != CAN_MTU)) {
> +	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || skb->len != CAN_MTU)) {
>   		pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d\n",
>   			     dev->type, skb->len);
>   		goto free_skb;
>   	}
>   
> @@ -704,11 +704,11 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev,
>   static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
>   		     struct packet_type *pt, struct net_device *orig_dev)
>   {
>   	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
>   
> -	if (unlikely(dev->type != ARPHRD_CAN || skb->len != CANFD_MTU)) {
> +	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || skb->len != CANFD_MTU)) {
>   		pr_warn_once("PF_CAN: dropped non conform CAN FD skbuff: dev type %d, len %d\n",
>   			     dev->type, skb->len);
>   		goto free_skb;
>   	}
>