| From | Ben Hutchings <> | Date | Sun, 29 Dec 2013 03:08:44 +0100 | Subject | [PATCH 3.2 172/185] HID: multitouch: validate indexes details |
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3.2.54-rc1 review patch. If anyone has any objections, please let me know.
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From: Benjamin Tissoires <benjamin.tissoires@redhat.com>
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> --- --- a/drivers/hid/hid-multitouch.c +++ b/drivers/hid/hid-multitouch.c @@ -66,7 +66,7 @@ struct mt_device { unsigned last_field_index; /* last field index of the report */ unsigned last_slot_field; /* the last field of a slot */ int last_mt_collection; /* last known mt-related collection */ - __s8 inputmode; /* InputMode HID feature, -1 if non-existent */ + __s16 inputmode; /* InputMode HID feature, -1 if non-existent */ __u8 num_received; /* how many contacts we received */ __u8 num_expected; /* expected last contact index */ __u8 maxcontacts;
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