[PATCH 5.4 068/104] Input: pegasus_notetaker - fix endpoint sanity check

[Greg Kroah-Hartman]

From: Johan Hovold <johan@xxxxxxxxxx>

commit bcfcb7f9b480dd0be8f0df2df17340ca92a03b98 upstream.

The driver was checking the number of endpoints of the first alternate
setting instead of the current one, something which could be used by a
malicious device (or USB descriptor fuzzer) to trigger a NULL-pointer
dereference.

Fixes: 1afca2b66aac ("Input: add Pegasus Notetaker tablet driver")
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Acked-by: Martin Kepplinger <martink@xxxxxxxxx>
Acked-by: Vladis Dronov <vdronov@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20191210113737.4016-2-johan@xxxxxxxxxx
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/input/tablet/pegasus_notetaker.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/input/tablet/pegasus_notetaker.c
+++ b/drivers/input/tablet/pegasus_notetaker.c
@@ -275,7 +275,7 @@ static int pegasus_probe(struct usb_inte
 		return -ENODEV;
 
 	/* Sanity check that the device has an endpoint */
-	if (intf->altsetting[0].desc.bNumEndpoints < 1) {
+	if (intf->cur_altsetting->desc.bNumEndpoints < 1) {
 		dev_err(&intf->dev, "Invalid number of endpoints\n");
 		return -EINVAL;
 	}