Re: [PATCH net] can: j1939: fix UAF for rx_kref of j1939_priv

From: Marc Kleine-Budde
Date: Sun Oct 17 2021 - 06:48:32 EST


On 26.09.2021 18:47:57, Ziyang Xuan wrote:
> 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")
> Reported-by: syzbot+85d9878b19c94f9019ad@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Ziyang Xuan <william.xuanziyang@xxxxxxxxxx>

Added to linux-can/testing, added stable on Cc.

Thanks,
Marc

--
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