From 3ea566422cbde9610c2734980d1286ab681bb40e Mon Sep 17 00:00:00 2001 From: Oliver Hartkopp Date: Wed, 16 Mar 2022 17:42:56 +0100 Subject: [PATCH] can: isotp: sanitize CAN ID checks in isotp_bind() 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") Link: https://lore.kernel.org/all/20220316164258.54155-1-socketcan@hartkopp.net Reported-by: syzbot+2339c27f5c66c652843e@syzkaller.appspotmail.com Signed-off-by: Oliver Hartkopp Signed-off-by: Marc Kleine-Budde --- net/can/isotp.c | 41 +++++++++++++++++++++-------------------- 1 file changed, 21 insertions(+), 20 deletions(-) diff --git a/net/can/isotp.c b/net/can/isotp.c index d4c0b47..1662103 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); @@ -1206,16 +1209,14 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len) ifindex = dev->ifindex; if (do_rx_reg) { - can_rx_register(net, dev, addr->can_addr.tp.rx_id, - SINGLE_MASK(addr->can_addr.tp.rx_id), + can_rx_register(net, dev, rx_id, SINGLE_MASK(rx_id), isotp_rcv, sk, "isotp", sk); /* no consecutive frame echo skb in flight */ so->cfecho = 0; /* register for echo skb's */ - can_rx_register(net, dev, addr->can_addr.tp.tx_id, - SINGLE_MASK(addr->can_addr.tp.tx_id), + can_rx_register(net, dev, tx_id, SINGLE_MASK(tx_id), isotp_rcv_echo, sk, "isotpe", sk); } @@ -1239,8 +1240,8 @@ 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: -- 2.7.4