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can: isotp: prevent race between isotp_bind() and isotp_setsockopt()

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A race condition was found in isotp_setsockopt() which allows to
change socket options after the socket was bound.
For the specific case of SF_BROADCAST support, this might lead to possible
use-after-free because can_rx_unregister() is not called.

Checking for the flag under the socket lock in isotp_bind() and taking
the lock in isotp_setsockopt() fixes the issue.

Fixes: 921ca574cd ("can: isotp: add SF_BROADCAST support for functional addressing")
Link: https://lore.kernel.org/r/trinity-e6ae9efa-9afb-4326-84c0-f3609b9b8168-1620773528307@3c-app-gmx-bs06
Reported-by: Norbert Slusarek <nslusarek@gmx.net>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Norbert Slusarek <nslusarek@gmx.net>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Norbert Slusarek 2021-05-12 00:43:54 +02:00 committed by Marc Kleine-Budde
parent 440c3247cb
commit 2b17c400ae
1 changed files with 34 additions and 17 deletions
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51
net/can/isotp.c
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@ -1062,19 +1062,6 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
if (len < ISOTP_MIN_NAMELEN)
return -EINVAL;
/* do not register frame reception for functional addressing */
if (so->opt.flags & CAN_ISOTP_SF_BROADCAST)
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)
return -EADDRNOTAVAIL;
if (addr->can_addr.tp.rx_id & (CAN_ERR_FLAG | CAN_RTR_FLAG))
return -EADDRNOTAVAIL;
}
if (addr->can_addr.tp.tx_id & (CAN_ERR_FLAG | CAN_RTR_FLAG))
return -EADDRNOTAVAIL;
@ -1083,6 +1070,23 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
lock_sock(sk);
/* do not register frame reception for functional addressing */
if (so->opt.flags & CAN_ISOTP_SF_BROADCAST)
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 (so->bound && addr->can_ifindex == so->ifindex &&
addr->can_addr.tp.rx_id == so->rxid &&
addr->can_addr.tp.tx_id == so->txid)
@ -1164,16 +1168,13 @@ static int isotp_getname(struct socket *sock, struct sockaddr *uaddr, int peer)
return ISOTP_MIN_NAMELEN;
}
static int isotp_setsockopt(struct socket *sock, int level, int optname,
static int isotp_setsockopt_locked(struct socket *sock, int level, int optname,
sockptr_t optval, unsigned int optlen)
{
struct sock *sk = sock->sk;
struct isotp_sock *so = isotp_sk(sk);
int ret = 0;
if (level != SOL_CAN_ISOTP)
return -EINVAL;
if (so->bound)
return -EISCONN;
@ -1248,6 +1249,22 @@ static int isotp_setsockopt(struct socket *sock, int level, int optname,
return ret;
}
static int isotp_setsockopt(struct socket *sock, int level, int optname,
sockptr_t optval, unsigned int optlen)
{
struct sock *sk = sock->sk;
int ret;
if (level != SOL_CAN_ISOTP)
return -EINVAL;
lock_sock(sk);
ret = isotp_setsockopt_locked(sock, level, optname, optval, optlen);
release_sock(sk);
return ret;
}
static int isotp_getsockopt(struct socket *sock, int level, int optname,
char __user *optval, int __user *optlen)
{