Commit c08eadca authored by Dongliang Mu's avatar Dongliang Mu Committed by Hans Verkuil
Browse files

media: em28xx: initialize refcount before kref_get 



The commit 47677e51("[media] em28xx: Only deallocate struct
em28xx after finishing all extensions") adds kref_get to many init
functions (e.g., em28xx_audio_init). However, kref_init is called too
late in em28xx_usb_probe, since em28xx_init_dev before will invoke
those init functions and call kref_get function. Then refcount bug
occurs in my local syzkaller instance.

Fix it by moving kref_init before em28xx_init_dev. This issue occurs
not only in dev but also dev->dev_next.

Fixes: 47677e51 ("[media] em28xx: Only deallocate struct em28xx after finishing all extensions")
Reported-by: default avatarsyzkaller <syzkaller@googlegroups.com>
Signed-off-by: default avatarDongliang Mu <mudongliangabcd@gmail.com>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
parent dca4f5fd

drivers/media/usb/em28xx/em28xx-cards.c

+4 −4
Original line number Diff line number Diff line
@@ -3936,6 +3936,8 @@ static int em28xx_usb_probe(struct usb_interface *intf, 
		goto err_free;

	}



	kref_init(&dev->ref);



	dev->devno = nr;

	dev->model = id->driver_info;

	dev->alt   = -1;
@@ -4036,6 +4038,8 @@ static int em28xx_usb_probe(struct usb_interface *intf, 
	}



	if (dev->board.has_dual_ts && em28xx_duplicate_dev(dev) == 0) {

		kref_init(&dev->dev_next->ref);



		dev->dev_next->ts = SECONDARY_TS;

		dev->dev_next->alt   = -1;

		dev->dev_next->is_audio_only = has_vendor_audio &&
@@ -4090,12 +4094,8 @@ static int em28xx_usb_probe(struct usb_interface *intf, 
			em28xx_write_reg(dev, 0x0b, 0x82);

			mdelay(100);

		}



		kref_init(&dev->dev_next->ref);

	}



	kref_init(&dev->ref);



	request_modules(dev);



	/*