netdev - [PATCH v2] can: af_can: fix NULL pointer dereference in can_rcv

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Date:   Tue,  6 Dec 2022 21:12:59 +0100
From:   Oliver Hartkopp <socketcan@...tkopp.net>
To:     linux-can@...r.kernel.org
Cc:     netdev@...r.kernel.org, Oliver Hartkopp <socketcan@...tkopp.net>,
        syzbot+2d7f58292cb5b29eb5ad@...kaller.appspotmail.com,
        Wei Chen <harperchen1110@...il.com>
Subject: [PATCH v2] can: af_can: fix NULL pointer dereference in can_rcv_filter

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.

Fixes: 4e096a18867a ("net: introduce CAN specific pointer in the struct net_device")
Reported-by: syzbot+2d7f58292cb5b29eb5ad@...kaller.appspotmail.com
Reported-by: Wei Chen <harperchen1110@...il.com>
Signed-off-by: Oliver Hartkopp <socketcan@...tkopp.net>
---

V2: fix misspeling detected by checkpatch

net/can/af_can.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/can/af_can.c b/net/can/af_can.c
index 27dcdcc0b808..c69168f11e44 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -675,11 +675,11 @@ 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)
 {
-	if (unlikely(dev->type != ARPHRD_CAN || (!can_is_can_skb(skb)))) {
+	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_can_skb(skb))) {
 		pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 
 		kfree_skb(skb);
 		return NET_RX_DROP;
@@ -690,11 +690,11 @@ 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)
 {
-	if (unlikely(dev->type != ARPHRD_CAN || (!can_is_canfd_skb(skb)))) {
+	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_canfd_skb(skb))) {
 		pr_warn_once("PF_CAN: dropped non conform CAN FD skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 
 		kfree_skb(skb);
 		return NET_RX_DROP;
@@ -705,11 +705,11 @@ static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
 }
 
 static int canxl_rcv(struct sk_buff *skb, struct net_device *dev,
 		     struct packet_type *pt, struct net_device *orig_dev)
 {
-	if (unlikely(dev->type != ARPHRD_CAN || (!can_is_canxl_skb(skb)))) {
+	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_canxl_skb(skb))) {
 		pr_warn_once("PF_CAN: dropped non conform CAN XL skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 
 		kfree_skb(skb);
 		return NET_RX_DROP;
-- 
2.30.2