diff options
| author | Lin Ma <linma@zju.edu.cn> | 2022-08-07 17:59:52 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-01-18 13:30:36 +0300 |
| commit | 219b44bf94203bd433aa91b7796475bf656348e5 (patch) | |
| tree | 47b1c4f87709e0b55f453544821359fdb06d1002 /drivers/media | |
| parent | b4d8fd008de1774d99a5b50acc03d92a1919c3a7 (diff) | |
| download | linux-219b44bf94203bd433aa91b7796475bf656348e5.tar.xz | |
media: dvbdev: adopts refcnt to avoid UAF
[ Upstream commit 0fc044b2b5e2d05a1fa1fb0d7f270367a7855d79 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/media')
| -rw-r--r-- | drivers/media/dvb-core/dvb_ca_en50221.c | 2 | ||||
| -rw-r--r-- | drivers/media/dvb-core/dvb_frontend.c | 2 | ||||
| -rw-r--r-- | drivers/media/dvb-core/dvbdev.c | 32 |
3 files changed, 27 insertions, 9 deletions
diff --git a/drivers/media/dvb-core/dvb_ca_en50221.c b/drivers/media/dvb-core/dvb_ca_en50221.c index 4d371cea0d5d..36afcea709a7 100644 --- a/drivers/media/dvb-core/dvb_ca_en50221.c +++ b/drivers/media/dvb-core/dvb_ca_en50221.c @@ -168,7 +168,7 @@ static void dvb_ca_private_free(struct dvb_ca_private *ca) { unsigned int i; - dvb_free_device(ca->dvbdev); + dvb_device_put(ca->dvbdev); for (i = 0; i < ca->slot_count; i++) vfree(ca->slot_info[i].rx_buffer.data); diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c index 1768c1b515b3..e0650bc2df61 100644 --- a/drivers/media/dvb-core/dvb_frontend.c +++ b/drivers/media/dvb-core/dvb_frontend.c @@ -147,7 +147,7 @@ static void __dvb_frontend_free(struct dvb_frontend *fe) struct dvb_frontend_private *fepriv = fe->frontend_priv; if (fepriv) - dvb_free_device(fepriv->dvbdev); + dvb_device_put(fepriv->dvbdev); dvb_frontend_invoke_release(fe, fe->ops.release); diff --git a/drivers/media/dvb-core/dvbdev.c b/drivers/media/dvb-core/dvbdev.c index d8f19a4d214a..bf527eda6f05 100644 --- a/drivers/media/dvb-core/dvbdev.c +++ b/drivers/media/dvb-core/dvbdev.c @@ -107,7 +107,7 @@ static int dvb_device_open(struct inode *inode, struct file *file) new_fops = fops_get(dvbdev->fops); if (!new_fops) goto fail; - file->private_data = dvbdev; + file->private_data = dvb_device_get(dvbdev); replace_fops(file, new_fops); if (file->f_op->open) err = file->f_op->open(inode, file); @@ -171,6 +171,9 @@ int dvb_generic_release(struct inode *inode, struct file *file) } dvbdev->users++; + + dvb_device_put(dvbdev); + return 0; } EXPORT_SYMBOL(dvb_generic_release); @@ -487,6 +490,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev, return -ENOMEM; } + kref_init(&dvbdev->ref); memcpy(dvbdev, template, sizeof(struct dvb_device)); dvbdev->type = type; dvbdev->id = id; @@ -518,7 +522,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev, #endif dvbdev->minor = minor; - dvb_minors[minor] = dvbdev; + dvb_minors[minor] = dvb_device_get(dvbdev); up_write(&minor_rwsem); ret = dvb_register_media_device(dvbdev, type, minor, demux_sink_pads); @@ -559,6 +563,7 @@ void dvb_remove_device(struct dvb_device *dvbdev) down_write(&minor_rwsem); dvb_minors[dvbdev->minor] = NULL; + dvb_device_put(dvbdev); up_write(&minor_rwsem); dvb_media_device_free(dvbdev); @@ -570,21 +575,34 @@ void dvb_remove_device(struct dvb_device *dvbdev) EXPORT_SYMBOL(dvb_remove_device); -void dvb_free_device(struct dvb_device *dvbdev) +static void dvb_free_device(struct kref *ref) { - if (!dvbdev) - return; + struct dvb_device *dvbdev = container_of(ref, struct dvb_device, ref); kfree (dvbdev->fops); kfree (dvbdev); } -EXPORT_SYMBOL(dvb_free_device); + + +struct dvb_device *dvb_device_get(struct dvb_device *dvbdev) +{ + kref_get(&dvbdev->ref); + return dvbdev; +} +EXPORT_SYMBOL(dvb_device_get); + + +void dvb_device_put(struct dvb_device *dvbdev) +{ + if (dvbdev) + kref_put(&dvbdev->ref, dvb_free_device); +} void dvb_unregister_device(struct dvb_device *dvbdev) { dvb_remove_device(dvbdev); - dvb_free_device(dvbdev); + dvb_device_put(dvbdev); } EXPORT_SYMBOL(dvb_unregister_device); |