HID: multitouch: validate indexes details
authorBenjamin Tissoires <benjamin.tissoires@redhat.com>
Wed, 11 Sep 2013 19:56:58 +0000 (21:56 +0200)
committerBen Hutchings <ben@decadent.org.uk>
Fri, 3 Jan 2014 04:33:34 +0000 (04:33 +0000)
commit0b568069764b25b7114b241c361a904838280639
treef148a12dc7ec051d3a7898c9d9d6e09f721e61bc
parentebca8c26fb22fca588fdcf5e5baa409da399247f
HID: multitouch: validate indexes details

commit 8821f5dc187bdf16cfb32ef5aa8c3035273fa79a upstream.

When working on report indexes, always validate that they are in bounds.
Without this, a HID device could report a malicious feature report that
could trick the driver into a heap overflow:

[  634.885003] usb 1-1: New USB device found, idVendor=0596, idProduct=0500
...
[  676.469629] BUG kmalloc-192 (Tainted: G        W   ): Redzone overwritten

Note that we need to change the indexes from s8 to s16 as they can
be between -1 and 255.

CVE-2013-2897

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
[bwh: Backported to 3.2: mt_device::{cc,cc_value,inputmode}_index do not
 exist and the corresponding indices do not need to be validated.
 mt_device::maxcontact_report_id does not exist either.  So all we need
 to do is to widen mt_device::inputmode.]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
drivers/hid/hid-multitouch.c