Messages in this thread Patch in this message | | | From | Duoming Zhou <> | Subject | [PATCH net v2] ax25: fix use-after-free bugs caused by ax25_ds_del_timer | Date | Fri, 29 Mar 2024 09:50:23 +0800 |
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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> --- Changes in v2: - Call timer_shutdown_sync() in ax25_dev_device_down().
net/ax25/ax25_dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c index c5462486dbc..282ec581c07 100644 --- a/net/ax25/ax25_dev.c +++ b/net/ax25/ax25_dev.c @@ -105,7 +105,7 @@ void ax25_dev_device_down(struct net_device *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 /* -- 2.17.1
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