| Message ID | 20240329015023.9223-1-duoming@zju.edu.cn (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | fd819ad3ecf6f3c232a06b27423ce9ed8c20da89 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v2] ax25: fix use-after-free bugs caused by ax25_ds_del_timer | expand |
On Fri, Mar 29, 2024 at 09:50:23AM +0800, Duoming Zhou wrote: > 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(). Thanks, as per my review of v1, I do think this is a correct approach to addressing a valid concern. But I would also value another set of eyes on the problem. Reviewed-by: Simon Horman <horms@kernel.org> > 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 >
Hello: This patch was applied to netdev/net.git (main) by Jakub Kicinski <kuba@kernel.org>: On Fri, 29 Mar 2024 09:50:23 +0800 you wrote: > 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: > > [...] Here is the summary with links: - [net,v2] ax25: fix use-after-free bugs caused by ax25_ds_del_timer https://git.kernel.org/netdev/net/c/fd819ad3ecf6 You are awesome, thank you!
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 /*
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(-)