6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Duoming Zhou duoming@zju.edu.cn
commit fd819ad3ecf6f3c232a06b27423ce9ed8c20da89 upstream.
When the ax25 device is detaching, the ax25_dev_device_down() calls ax25_ds_del_timer() to cleanup the slave_timer. When the timer handler is running, the ax25_ds_del_timer() that calls del_timer() in it will return directly. As a result, the use-after-free bugs could happen, one of the scenarios is shown below:
(Thread 1) | (Thread 2) | ax25_ds_timeout() ax25_dev_device_down() | ax25_ds_del_timer() | del_timer() | ax25_dev_put() //FREE | | ax25_dev-> //USE
In order to mitigate bugs, when the device is detaching, use timer_shutdown_sync() to stop the timer.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Duoming Zhou duoming@zju.edu.cn Reviewed-by: Simon Horman horms@kernel.org Link: https://lore.kernel.org/r/20240329015023.9223-1-duoming@zju.edu.cn Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ax25/ax25_dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/ax25/ax25_dev.c +++ b/net/ax25/ax25_dev.c @@ -105,7 +105,7 @@ void ax25_dev_device_down(struct net_dev spin_lock_bh(&ax25_dev_lock);
#ifdef CONFIG_AX25_DAMA_SLAVE - ax25_ds_del_timer(ax25_dev); + timer_shutdown_sync(&ax25_dev->dama.slave_timer); #endif
/*