From dc9bf4ee9ad3e29a9ae42e2ae0da5c104108d0dd Mon Sep 17 00:00:00 2001
From: Oliver Hartkopp <socketcan@hartkopp.net>
Date: Thu, 17 Mar 2022 14:19:48 +0100
Subject: [PATCH] can: isotp: sanitize CAN ID checks in isotp_bind()

Upstream commit https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=3ea566422cbd

Syzbot created an environment that lead to a state machine status that
can not be reached with a compliant CAN ID address configuration.
The provided address information consisted of CAN ID 0x6000001 and 0xC28001
which both boil down to 11 bit CAN IDs 0x001 in sending and receiving.

Sanitize the SFF/EFF CAN ID values before performing the address checks.

Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
Reported-by: syzbot+2339c27f5c66c652843e@syzkaller.appspotmail.com
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 net/can/isotp.c | 41 ++++++++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 19 deletions(-)

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 02f516a..520d20f 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1148,6 +1148,7 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 	struct net *net = sock_net(sk);
 	int ifindex;
 	struct net_device *dev;
+	canid_t tx_id, rx_id;
 	int err = 0;
 	int notify_enetdown = 0;
 	int do_rx_reg = 1;
@@ -1155,8 +1156,18 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 	if (len < ISOTP_MIN_NAMELEN)
 		return -EINVAL;
 
-	if (addr->can_addr.tp.tx_id & (CAN_ERR_FLAG | CAN_RTR_FLAG))
-		return -EADDRNOTAVAIL;
+	/* sanitize tx/rx CAN identifiers */
+	tx_id = addr->can_addr.tp.tx_id;
+	if (tx_id & CAN_EFF_FLAG)
+		tx_id &= (CAN_EFF_FLAG | CAN_EFF_MASK);
+	else
+		tx_id &= CAN_SFF_MASK;
+
+	rx_id = addr->can_addr.tp.rx_id;
+	if (rx_id & CAN_EFF_FLAG)
+		rx_id &= (CAN_EFF_FLAG | CAN_EFF_MASK);
+	else
+		rx_id &= CAN_SFF_MASK;
 
 	if (!addr->can_ifindex)
 		return -ENODEV;
@@ -1168,21 +1179,13 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 		do_rx_reg = 0;
 
 	/* do not validate rx address for functional addressing */
-	if (do_rx_reg) {
-		if (addr->can_addr.tp.rx_id == addr->can_addr.tp.tx_id) {
-			err = -EADDRNOTAVAIL;
-			goto out;
-		}
-
-		if (addr->can_addr.tp.rx_id & (CAN_ERR_FLAG | CAN_RTR_FLAG)) {
-			err = -EADDRNOTAVAIL;
-			goto out;
-		}
+	if (do_rx_reg && rx_id == tx_id) {
+		err = -EADDRNOTAVAIL;
+		goto out;
 	}
 
 	if (so->bound && addr->can_ifindex == so->ifindex &&
-	    addr->can_addr.tp.rx_id == so->rxid &&
-	    addr->can_addr.tp.tx_id == so->txid)
+	    rx_id == so->rxid && tx_id == so->txid)
 		goto out;
 
 	dev = dev_get_by_index(net, addr->can_ifindex);
@@ -1207,11 +1210,11 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 
 	if (do_rx_reg)
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4,12,0)
-		can_rx_register(net, dev, addr->can_addr.tp.rx_id,
+		can_rx_register(net, dev, rx_id,
 #else
-		can_rx_register(dev, addr->can_addr.tp.rx_id,
+		can_rx_register(dev, rx_id,
 #endif
-				SINGLE_MASK(addr->can_addr.tp.rx_id), isotp_rcv, sk,
+				SINGLE_MASK(rx_id), isotp_rcv, sk,
 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,9,11)) || \
 	((LINUX_VERSION_CODE >= KERNEL_VERSION(4,4,50)) && (LINUX_VERSION_CODE < KERNEL_VERSION(4, 5, 0))) || \
 	((LINUX_VERSION_CODE >= KERNEL_VERSION(3,18,49)) && (LINUX_VERSION_CODE < KERNEL_VERSION(3, 19, 0))) || \
@@ -1241,8 +1244,8 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 
 	/* switch to new settings */
 	so->ifindex = ifindex;
-	so->rxid = addr->can_addr.tp.rx_id;
-	so->txid = addr->can_addr.tp.tx_id;
+	so->rxid = rx_id;
+	so->txid = tx_id;
 	so->bound = 1;
 
 out: