[ 10/49] HID: validate feature and input report details

Greg Kroah-Hartman
2013-09-29T19:28:04Z

From: Benjamin Tissoires <benjamin.tissoires@redhat.com>

commit cc6b54aa54bf40b762cab45a9fc8aa81653146eb upstream.

When dealing with usage_index, be sure to properly use unsigned instead of
int to avoid overflows.

When working on report fields, always validate that their report_counts 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: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hid/hid-core.c | 16 +++++++---------
drivers/hid/hid-input.c | 11 ++++++++++-
2 files changed, 17 insertions(+), 10 deletions(-)

--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -94,7 +94,6 @@ EXPORT_SYMBOL_GPL(hid_register_report);
static struct hid_field *hid_register_field(struct hid_report *report, unsigned usages, unsigned values)
{
struct hid_field *field;
- int i;

if (report->maxfield == HID_MAX_FIELDS) {
hid_err(report->device, "too many fields in report\n");
@@ -113,9 +112,6 @@ static struct hid_field *hid_register_fi
field->value = (s32 *)(field->usage + usages);
field->report = report;

- for (i = 0; i < usages; i++)
- field->usage[i].usage_index = i;
-
return field;
}

@@ -226,9 +222,9 @@ static int hid_add_field(struct hid_pars
{
struct hid_report *report;
struct hid_field *field;
- int usages;
+ unsigned usages;
unsigned offset;
- int i;
+ unsigned i;

report = hid_register_report(parser->device, report_type, parser->global.report_id);
if (!report) {
@@ -255,7 +251,8 @@ static int hid_add_field(struct hid_pars
if (!parser->local.usage_index) /* Ignore padding fields */
return 0;

- usages = max_t(int, parser->local.usage_index, parser->global.report_count);
+ usages = max_t(unsigned, parser->local.usage_index,
+ parser->global.report_count);

field = hid_register_field(report, usages, parser->global.report_count);
if (!field)
@@ -266,13 +263,14 @@ static int hid_add_field(struct hid_pars
field->application = hid_lookup_collection(parser, HID_COLLECTION_APPLICATION);

for (i = 0; i < usages; i++) {
- int j = i;
+ unsigned j = i;
/* Duplicate the last usage we parsed if we have excess values */
if (i >= parser->local.usage_index)
j = parser->local.usage_index - 1;
field->usage[i].hid = parser->local.usage[j];
field->usage[i].collection_index =
parser->local.collection_index[j];
+ field->usage[i].usage_index = i;
}

field->maxusage = usages;
@@ -1295,7 +1293,7 @@ int hid_report_raw_event(struct hid_devi
goto out;
}

- if (hid->claimed != HID_CLAIMED_HIDRAW) {
+ if (hid->claimed != HID_CLAIMED_HIDRAW && report->maxfield) {
for (a = 0; a < report->maxfield; a++)
hid_input_field(hid, report->field[a], cdata, interrupt);
hdrv = hid->driver;
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -485,6 +485,10 @@ static void hidinput_configure_usage(str
if (field->flags & HID_MAIN_ITEM_CONSTANT)
goto ignore;

+ /* Ignore if report count is out of bounds. */
+ if (field->report_count < 1)
+ goto ignore;
+
/* only LED usages are supported in output fields */
if (field->report_type == HID_OUTPUT_REPORT &&
(usage->hid & HID_USAGE_PAGE) != HID_UP_LED) {
@@ -1163,7 +1167,11 @@ static void report_features(struct hid_d

rep_enum = &hid->report_enum[HID_FEATURE_REPORT];
list_for_each_entry(rep, &rep_enum->report_list, list)
- for (i = 0; i < rep->maxfield; i++)
+ for (i = 0; i < rep->maxfield; i++) {
+ /* Ignore if report count is out of bounds. */
+ if (rep->field[i]->report_count < 1)
+ continue;
+
for (j = 0; j < rep->field[i]->maxusage; j++) {
/* Verify if Battery Strength feature is available */
hidinput_setup_battery(hid, HID_FEATURE_REPORT, rep->field[i]);
@@ -1172,6 +1180,7 @@ static void report_features(struct hid_d
drv->feature_mapping(hid, rep->field[i],
rep->field[i]->usage + j);
}
+ }
}

static struct hid_input *hidinput_allocate(struct hid_device *hid)