4.4-stable review patch. If anyone has any objections, please let me know.
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From: Dmitry Torokhov dmitry.torokhov@gmail.com
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@google.com Signed-off-by: Dmitry Torokhov dmitry.torokhov@gmail.com Cc: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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;