From: Kees Cook <[email protected]> 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 CVE-2013-2897 Signed-off-by: Kees Cook <[email protected]> Cc: [email protected] --- drivers/hid/hid-multitouch.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c index cb0e361..2aa275e 100644 --- a/drivers/hid/hid-multitouch.c +++ b/drivers/hid/hid-multitouch.c @@ -330,9 +330,18 @@ static void mt_feature_mapping(struct hid_device *hdev, break; } } + /* Ignore if value index is out of bounds. */ + if (td->inputmode_index < 0 || + td->inputmode_index >= field->report_count) { + dev_err(&hdev->dev, "HID_DG_INPUTMODE out of range\n"); + td->inputmode = -1; + } break; case HID_DG_CONTACTMAX: + /* Ignore if value count is out of bounds. */ + if (field->report_count < 1) + break; td->maxcontact_report_id = field->report->id; td->maxcontacts = field->value[0]; if (!td->maxcontacts && @@ -743,15 +752,21 @@ static void mt_touch_report(struct hid_device *hid, struct hid_report *report) unsigned count; int r, n; + if (report->maxfield == 0) + return; + /* * Includes multi-packet support where subsequent * packets are sent with zero contactcount. */ - if (td->cc_index >= 0) { - struct hid_field *field = report->field[td->cc_index]; - int value = field->value[td->cc_value_index]; - if (value) - td->num_expected = value; + if (td->cc_index >= 0 && td->cc_index < report->maxfield) { + field = report->field[td->cc_index]; + if (td->cc_value_index >= 0 && + td->cc_value_index < field->report_count) { + int value = field->value[td->cc_value_index]; + if (value) + td->num_expected = value; + } } for (r = 0; r < report->maxfield; r++) { -- Jiri Kosina SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
