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| author | Lin Ma <linma@zju.edu.cn> | 2022-08-07 17:59:52 +0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@kernel.org> | 2022-11-25 13:08:23 +0300 |
| commit | 0fc044b2b5e2d05a1fa1fb0d7f270367a7855d79 (patch) | |
| tree | bbf176c361eb5d46f8b79d923239f42363c5ba9a /include/media | |
| parent | 9b7de3c2daf503f86ab0641f377402b8d7f5e485 (diff) | |
| download | linux-0fc044b2b5e2d05a1fa1fb0d7f270367a7855d79.tar.xz | |
media: dvbdev: adopts refcnt to avoid UAF
dvb_unregister_device() is known that prone to use-after-free.
That is, the cleanup from dvb_unregister_device() releases the dvb_device
even if there are pointers stored in file->private_data still refer to it.
This patch adds a reference counter into struct dvb_device and delays its
deallocation until no pointer refers to the object.
Link: https://lore.kernel.org/linux-media/20220807145952.10368-1-linma@zju.edu.cn
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Diffstat (limited to 'include/media')
| -rw-r--r-- | include/media/dvbdev.h | 31 |
1 files changed, 17 insertions, 14 deletions
diff --git a/include/media/dvbdev.h b/include/media/dvbdev.h index 6ccff7c6fa6b..fad9871157e2 100644 --- a/include/media/dvbdev.h +++ b/include/media/dvbdev.h @@ -160,6 +160,7 @@ struct dvb_adapter { */ struct dvb_device { struct list_head list_head; + struct kref ref; const struct file_operations *fops; struct dvb_adapter *adapter; enum dvb_device_type type; @@ -192,6 +193,20 @@ struct dvb_device { }; /** + * dvb_device_get - Increase dvb_device reference + * + * @dvbdev: pointer to struct dvb_device + */ +struct dvb_device *dvb_device_get(struct dvb_device *dvbdev); + +/** + * dvb_device_get - Decrease dvb_device reference + * + * @dvbdev: pointer to struct dvb_device + */ +void dvb_device_put(struct dvb_device *dvbdev); + +/** * dvb_register_adapter - Registers a new DVB adapter * * @adap: pointer to struct dvb_adapter @@ -235,29 +250,17 @@ int dvb_register_device(struct dvb_adapter *adap, /** * dvb_remove_device - Remove a registered DVB device * - * This does not free memory. To do that, call dvb_free_device(). + * This does not free memory. dvb_free_device() will do that when + * reference counter is empty * * @dvbdev: pointer to struct dvb_device */ void dvb_remove_device(struct dvb_device *dvbdev); -/** - * dvb_free_device - Free memory occupied by a DVB device. - * - * Call dvb_unregister_device() before calling this function. - * - * @dvbdev: pointer to struct dvb_device - */ -void dvb_free_device(struct dvb_device *dvbdev); /** * dvb_unregister_device - Unregisters a DVB device * - * This is a combination of dvb_remove_device() and dvb_free_device(). - * Using this function is usually a mistake, and is often an indicator - * for a use-after-free bug (when a userspace process keeps a file - * handle to a detached device). - * * @dvbdev: pointer to struct dvb_device */ void dvb_unregister_device(struct dvb_device *dvbdev); |