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![]() The ax25_disconnect() in ax25_kill_by_device() is not protected by any locks, thus there is a race condition between ax25_disconnect() and ax25_destroy_socket(). when ax25->sk is assigned as NULL by ax25_destroy_socket(), a NULL pointer dereference bug will occur if site (1) or (2) dereferences ax25->sk. ax25_kill_by_device() | ax25_release() ax25_disconnect() | ax25_destroy_socket() ... | if(ax25->sk != NULL) | ... ... | ax25->sk = NULL; bh_lock_sock(ax25->sk); //(1) | ... ... | bh_unlock_sock(ax25->sk); //(2)| This patch moves ax25_disconnect() into lock_sock(), which can synchronize with ax25_destroy_socket() in ax25_release(). Fail log: =============================================================== BUG: kernel NULL pointer dereference, address: 0000000000000088 ... RIP: 0010:_raw_spin_lock+0x7e/0xd0 ... Call Trace: ax25_disconnect+0xf6/0x220 ax25_device_event+0x187/0x250 raw_notifier_call_chain+0x5e/0x70 dev_close_many+0x17d/0x230 rollback_registered_many+0x1f1/0x950 unregister_netdevice_queue+0x133/0x200 unregister_netdev+0x13/0x20 ... Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> Signed-off-by: David S. Miller <davem@davemloft.net> |
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.. | ||
af_ax25.c | ||
ax25_addr.c | ||
ax25_dev.c | ||
ax25_ds_in.c | ||
ax25_ds_subr.c | ||
ax25_ds_timer.c | ||
ax25_iface.c | ||
ax25_in.c | ||
ax25_ip.c | ||
ax25_out.c | ||
ax25_route.c | ||
ax25_std_in.c | ||
ax25_std_subr.c | ||
ax25_std_timer.c | ||
ax25_subr.c | ||
ax25_timer.c | ||
ax25_uid.c | ||
Kconfig | ||
Makefile | ||
sysctl_net_ax25.c |