Add hdpvr device num check and error handling
We need to increment the device count atomically before we checkout a
device to make sure that we do not reach the max count, otherwise we get
out-of-bounds errors as reported by syzbot.
Reported-and-tested-by: syzbot+aac8d0d7205f112045d2@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Luke Nowakowski-Krijger <lnowakow@xxxxxxxxxxxx>
---
Changes in V1:
+ add storing of incremented index in dev_num var
+ add bounds check on dev_num and appropriate error handling
- remove attomic_inc_return from inside of hdpvr_register call
drivers/media/usb/hdpvr/hdpvr-core.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/media/usb/hdpvr/hdpvr-core.c b/drivers/media/usb/hdpvr/hdpvr-core.c
index 29ac7fc5b039..640ef83b57c9 100644
--- a/drivers/media/usb/hdpvr/hdpvr-core.c
+++ b/drivers/media/usb/hdpvr/hdpvr-core.c
@@ -275,6 +275,7 @@ static int hdpvr_probe(struct usb_interface *interface,
#endif
size_t buffer_size;
int i;
+ int dev_num;
int retval = -ENOMEM;
/* allocate memory for our device state and initialize it */
@@ -371,9 +372,18 @@ static int hdpvr_probe(struct usb_interface *interface,
goto reg_fail;
}
#endif
-
+
+ dev_num = atomic_inc_return(&dev_nr);
+ if (dev_num >= HDPVR_MAX) {
+ v4l2_err(&dev->v4l2_dev,
+ "max device number reached, device register failed\n");
+ atomic_dec(&dev_nr);
+ retval = -ENODEV;
+ goto reg_fail;
+ }
+
retval = hdpvr_register_videodev(dev, &interface->dev,
- video_nr[atomic_inc_return(&dev_nr)]);
+ video_nr[dev_num]);
if (retval < 0) {
v4l2_err(&dev->v4l2_dev, "registering videodev failed\n");
goto reg_fail;
--
2.20.1
