diff options
| author | Sean Young <sean@mess.org> | 2020-08-08 14:19:12 +0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2020-08-28 15:06:35 +0300 |
| commit | 4f0835d6677dc69263f90f976524cb92b257d9f4 (patch) | |
| tree | 8770fcd8530254e36a605179dee74ae4306b32bf | |
| parent | 8a30c017c99603b216907c2f7aa22d3afe4137c3 (diff) | |
| download | linux-4f0835d6677dc69263f90f976524cb92b257d9f4.tar.xz | |
media: rc: uevent sysfs file races with rc_unregister_device()
Only report uevent file contents if device still registered, else we
might read freed memory.
Reported-by: syzbot+ceef16277388d6f24898@syzkaller.appspotmail.com
Cc: Hillf Danton <hdanton@sina.com>
Cc: <stable@vger.kernel.org> # 4.16+
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
| -rw-r--r-- | drivers/media/rc/rc-main.c | 32 |
1 files changed, 16 insertions, 16 deletions
diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c index 7b53066d9d07..e1cda80a4b25 100644 --- a/drivers/media/rc/rc-main.c +++ b/drivers/media/rc/rc-main.c @@ -1601,25 +1601,25 @@ static void rc_dev_release(struct device *device) kfree(dev); } -#define ADD_HOTPLUG_VAR(fmt, val...) \ - do { \ - int err = add_uevent_var(env, fmt, val); \ - if (err) \ - return err; \ - } while (0) - static int rc_dev_uevent(struct device *device, struct kobj_uevent_env *env) { struct rc_dev *dev = to_rc_dev(device); + int ret = 0; - if (dev->rc_map.name) - ADD_HOTPLUG_VAR("NAME=%s", dev->rc_map.name); - if (dev->driver_name) - ADD_HOTPLUG_VAR("DRV_NAME=%s", dev->driver_name); - if (dev->device_name) - ADD_HOTPLUG_VAR("DEV_NAME=%s", dev->device_name); + mutex_lock(&dev->lock); - return 0; + if (!dev->registered) + ret = -ENODEV; + if (ret == 0 && dev->rc_map.name) + ret = add_uevent_var(env, "NAME=%s", dev->rc_map.name); + if (ret == 0 && dev->driver_name) + ret = add_uevent_var(env, "DRV_NAME=%s", dev->driver_name); + if (ret == 0 && dev->device_name) + ret = add_uevent_var(env, "DEV_NAME=%s", dev->device_name); + + mutex_unlock(&dev->lock); + + return ret; } /* @@ -2011,14 +2011,14 @@ void rc_unregister_device(struct rc_dev *dev) del_timer_sync(&dev->timer_keyup); del_timer_sync(&dev->timer_repeat); - rc_free_rx_device(dev); - mutex_lock(&dev->lock); if (dev->users && dev->close) dev->close(dev); dev->registered = false; mutex_unlock(&dev->lock); + rc_free_rx_device(dev); + /* * lirc device should be freed with dev->registered = false, so * that userspace polling will get notified. |