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Input: ims-psu - check if CDC union descriptor is sane 

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@google.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Dmitry Torokhov 2017-10-07 11:07:47 -07:00
parent 20ac95d52a
commit ea04efee76
1 changed files with 14 additions and 2 deletions
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14
drivers/input/misc/ims-pcu.c
View File

@ -1635,13 +1635,25 @@ ims_pcu_get_cdc_union_desc(struct usb_interface *intf)
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");
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;