[PATCH 5.14 072/169] can: j1939: j1939_netdev_start(): fix UAF for rx_kref of j1939_priv

Greg Kroah-Hartman
2021-10-25T19:49:43Z

From: Ziyang Xuan <william.xuanziyang@huawei.com>

commit d9d52a3ebd284882f5562c88e55991add5d01586 upstream.

It will trigger UAF for rx_kref of j1939_priv as following.

cpu0 cpu1
j1939_sk_bind(socket0, ndev0, ...)
j1939_netdev_start
j1939_sk_bind(socket1, ndev0, ...)
j1939_netdev_start
j1939_priv_set
j1939_priv_get_by_ndev_locked
j1939_jsk_add
.....
j1939_netdev_stop
kref_put_lock(&priv->rx_kref, ...)
kref_get(&priv->rx_kref, ...)
REFCOUNT_WARN("addition on 0;...")

====================================================
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 20874 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0
RIP: 0010:refcount_warn_saturate+0x169/0x1e0
Call Trace:
j1939_netdev_start+0x68b/0x920
j1939_sk_bind+0x426/0xeb0
? security_socket_bind+0x83/0xb0

The rx_kref's kref_get() and kref_put() should use j1939_netdev_lock to
protect.

Fixes: 9d71dd0c70099 ("can: add support of SAE J1939 protocol")
Link: https://lore.kernel.org/all/20210926104757.2021540-1-william.xuanziyang@huawei.com
Cc: stable@vger.kernel.org
Reported-by: syzbot+85d9878b19c94f9019ad@syzkaller.appspotmail.com
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/can/j1939/main.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

--- a/net/can/j1939/main.c
+++ b/net/can/j1939/main.c
@@ -249,11 +249,14 @@ struct j1939_priv *j1939_netdev_start(st
struct j1939_priv *priv, *priv_new;
int ret;

- priv = j1939_priv_get_by_ndev(ndev);
+ spin_lock(&j1939_netdev_lock);
+ priv = j1939_priv_get_by_ndev_locked(ndev);
if (priv) {
kref_get(&priv->rx_kref);
+ spin_unlock(&j1939_netdev_lock);
return priv;
}
+ spin_unlock(&j1939_netdev_lock);

priv = j1939_priv_create(ndev);
if (!priv)
@@ -269,10 +272,10 @@ struct j1939_priv *j1939_netdev_start(st
/* Someone was faster than us, use their priv and roll
* back our's.
*/
+ kref_get(&priv_new->rx_kref);
spin_unlock(&j1939_netdev_lock);
dev_put(ndev);
kfree(priv);
- kref_get(&priv_new->rx_kref);
return priv_new;
}
j1939_priv_set(ndev, priv);