CVE-2021-47459

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> can: j1939: j1939_netdev_start(): fix UAF for rx_kref of j1939_priv<br /> <br /> It will trigger UAF for rx_kref of j1939_priv as following.<br /> <br /> cpu0 cpu1<br /> j1939_sk_bind(socket0, ndev0, ...)<br /> j1939_netdev_start<br /> j1939_sk_bind(socket1, ndev0, ...)<br /> j1939_netdev_start<br /> j1939_priv_set<br /> j1939_priv_get_by_ndev_locked<br /> j1939_jsk_add<br /> .....<br /> j1939_netdev_stop<br /> kref_put_lock(&amp;priv-&gt;rx_kref, ...)<br /> kref_get(&amp;priv-&gt;rx_kref, ...)<br /> REFCOUNT_WARN("addition on 0;...")<br /> <br /> ====================================================<br /> refcount_t: addition on 0; use-after-free.<br /> WARNING: CPU: 1 PID: 20874 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0<br /> RIP: 0010:refcount_warn_saturate+0x169/0x1e0<br /> Call Trace:<br /> j1939_netdev_start+0x68b/0x920<br /> j1939_sk_bind+0x426/0xeb0<br /> ? security_socket_bind+0x83/0xb0<br /> <br /> The rx_kref&amp;#39;s kref_get() and kref_put() should use j1939_netdev_lock to<br /> protect.