In some device configurations there's no radio or radio support in the
driver. That's OK, as the driver sets itself up accordingly. However
on tear-down in these caes it's still trying to tear down radio
related context when there isn't anything there, leading to
dereferences through a null pointer and chaos follows.
How this bug survived unfixed for 11 years in the pvrusb2 driver is a
mystery to me.
Signed-off-by: Mike Isely <isely@xxxxxxxxx>
---
drivers/media/usb/pvrusb2/pvrusb2-v4l2.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c b/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
index aa4fbc3e88cc..339119f6cc23 100644
--- a/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
+++ b/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
@@ -909,8 +909,12 @@ static void pvr2_v4l2_internal_check(struct pvr2_channel *chp)
pvr2_v4l2_dev_disassociate_parent(vp->dev_video);
pvr2_v4l2_dev_disassociate_parent(vp->dev_radio);
if (!list_empty(&vp->dev_video->devbase.fh_list) ||
- !list_empty(&vp->dev_radio->devbase.fh_list))
+ ((vp->dev_radio != NULL) &&
+ !list_empty(&vp->dev_radio->devbase.fh_list))) {
+ pvr2_trace(PVR2_TRACE_STRUCT,
+ "pvr2_v4l2 internal_check exit-empty id=%p", vp);
return;
+ }
pvr2_v4l2_destroy_no_lock(vp);
}
@@ -946,7 +950,8 @@ static int pvr2_v4l2_release(struct file *file)
kfree(fhp);
if (vp->channel.mc_head->disconnect_flag &&
list_empty(&vp->dev_video->devbase.fh_list) &&
- list_empty(&vp->dev_radio->devbase.fh_list)) {
+ ((vp->dev_radio == NULL) ||
+ list_empty(&vp->dev_radio->devbase.fh_list))) {
pvr2_v4l2_destroy_no_lock(vp);
}
return 0;
--
2.20.1
