From 8821f5dc187bdf16cfb32ef5aa8c3035273fa79a Mon Sep 17 00:00:00 2001 From: Benjamin Tissoires Date: Wed, 11 Sep 2013 21:56:58 +0200 Subject: [PATCH] HID: multitouch: validate indexes details 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 Cc: stable@vger.kernel.org Signed-off-by: Benjamin Tissoires Acked-by: Kees Cook Signed-off-by: Jiri Kosina --- drivers/hid/hid-multitouch.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c index ac28f08..5e5fe1b 100644 --- a/drivers/hid/hid-multitouch.c +++ b/drivers/hid/hid-multitouch.c @@ -101,9 +101,9 @@ struct mt_device { unsigned last_slot_field; /* the last field of a slot */ unsigned mt_report_id; /* the report ID of the multitouch device */ unsigned pen_report_id; /* the report ID of the pen device */ - __s8 inputmode; /* InputMode HID feature, -1 if non-existent */ - __s8 inputmode_index; /* InputMode HID feature index in the report */ - __s8 maxcontact_report_id; /* Maximum Contact Number HID feature, + __s16 inputmode; /* InputMode HID feature, -1 if non-existent */ + __s16 inputmode_index; /* InputMode HID feature index in the report */ + __s16 maxcontact_report_id; /* Maximum Contact Number HID feature, -1 if non-existent */ __u8 num_received; /* how many contacts we received */ __u8 num_expected; /* expected last contact index */ @@ -312,20 +312,18 @@ static void mt_feature_mapping(struct hid_device *hdev, struct hid_field *field, struct hid_usage *usage) { struct mt_device *td = hid_get_drvdata(hdev); - int i; switch (usage->hid) { case HID_DG_INPUTMODE: - td->inputmode = field->report->id; - td->inputmode_index = 0; /* has to be updated below */ - - for (i=0; i < field->maxusage; i++) { - if (field->usage[i].hid == usage->hid) { - td->inputmode_index = i; - break; - } + /* Ignore if value index is out of bounds. */ + if (usage->usage_index >= field->report_count) { + dev_err(&hdev->dev, "HID_DG_INPUTMODE out of range\n"); + break; } + td->inputmode = field->report->id; + td->inputmode_index = usage->usage_index; + break; case HID_DG_CONTACTMAX: td->maxcontact_report_id = field->report->id; @@ -511,6 +509,10 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi, mt_store_field(usage, td, hi); return 1; case HID_DG_CONTACTCOUNT: + /* Ignore if indexes are out of bounds. */ + if (field->index >= field->report->maxfield || + usage->usage_index >= field->report_count) + return 1; td->cc_index = field->index; td->cc_value_index = usage->usage_index; return 1; -- 2.7.4