4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
commit ea04efee7635c9120d015dcdeeeb6988130cb67a upstream.
Before trying to use CDC union descriptor, try to validate whether that it
is sane by checking that intf->altsetting->extra is big enough and that
descriptor bLength is not too big and not too small.
Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Cc: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/input/misc/ims-pcu.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
--- a/drivers/input/misc/ims-pcu.c
+++ b/drivers/input/misc/ims-pcu.c
@@ -1635,13 +1635,25 @@ ims_pcu_get_cdc_union_desc(struct usb_in
return NULL;
}
- while (buflen > 0) {
+ while (buflen >= sizeof(*union_desc)) {
union_desc = (struct usb_cdc_union_desc *)buf;
+ if (union_desc->bLength > buflen) {
+ dev_err(&intf->dev, "Too large descriptor\n");
+ return NULL;
+ }
+
if (union_desc->bDescriptorType == USB_DT_CS_INTERFACE &&
union_desc->bDescriptorSubType == USB_CDC_UNION_TYPE) {
dev_dbg(&intf->dev, "Found union header\n");
- return union_desc;
+
+ if (union_desc->bLength >= sizeof(*union_desc))
+ return union_desc;
+
+ dev_err(&intf->dev,
+ "Union descriptor to short (%d vs %zd\n)",
+ union_desc->bLength, sizeof(*union_desc));
+ return NULL;
}
buflen -= union_desc->bLength;