The dvbdev contains a static variable used to store dvb minors.
The behavior of it depends if CONFIG_DVB_DYNAMIC_MINORS is set or not. When not set, dvb_register_device() won't check for boundaries, as it will rely that a previous call to dvb_register_adapter() would already be enforcing it.
On a similar way, dvb_device_open() uses the assumption that the register functions already did the needed checks.
This can be fragile if some device ends using different calls. This also generate warnings on static check analysers.
So, add explicit guards to prevent potential risk of OOM issues.
Fixes: 5dd3f3071070 ("V4L/DVB (9361): Dynamic DVB minor allocation") Cc: stable@vger.kernel.org Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org --- drivers/media/dvb-core/dvbdev.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/media/dvb-core/dvbdev.c b/drivers/media/dvb-core/dvbdev.c index b43695bc51e7..14f323fbada7 100644 --- a/drivers/media/dvb-core/dvbdev.c +++ b/drivers/media/dvb-core/dvbdev.c @@ -86,10 +86,15 @@ static DECLARE_RWSEM(minor_rwsem); static int dvb_device_open(struct inode *inode, struct file *file) { struct dvb_device *dvbdev; + unsigned int minor = iminor(inode); + + if (minor >= MAX_DVB_MINORS) + return -ENODEV;
mutex_lock(&dvbdev_mutex); down_read(&minor_rwsem); - dvbdev = dvb_minors[iminor(inode)]; + + dvbdev = dvb_minors[minor];
if (dvbdev && dvbdev->fops) { int err = 0; @@ -525,7 +530,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev, for (minor = 0; minor < MAX_DVB_MINORS; minor++) if (!dvb_minors[minor]) break; - if (minor == MAX_DVB_MINORS) { + if (minor >= MAX_DVB_MINORS) { if (new_node) { list_del(&new_node->list_head); kfree(dvbdevfops); @@ -540,6 +545,14 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev, } #else minor = nums2minor(adap->num, type, id); + if (minor >= MAX_DVB_MINORS) { + dvb_media_device_free(dvbdev); + list_del(&dvbdev->list_head); + kfree(dvbdev); + *pdvbdev = NULL; + mutex_unlock(&dvbdev_register_lock); + return ret; + } #endif dvbdev->minor = minor; dvb_minors[minor] = dvb_device_get(dvbdev);