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media: hdpvr: Add device num check and handling 

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@syzkaller.appspotmail.com

Signed-off-by: Luke Nowakowski-Krijger <lnowakow@eng.ucsd.edu>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Luke Nowakowski-Krijger 2019-07-17 10:19:46 -04:00 committed by Mauro Carvalho Chehab
parent 9e037bdf74
commit d4a6a9537b
1 changed files with 11 additions and 1 deletions
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12
drivers/media/usb/hdpvr/hdpvr-core.c
View File

@ -271,6 +271,7 @@ 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 */
@ -368,8 +369,17 @@ static int hdpvr_probe(struct usb_interface *interface,
}
#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;