[PATCH 4.4 054/146] HID: hiddev: validate num_values for HIDIOCGUSAGES, HIDIOCSUSAGES commands

Greg Kroah-Hartman
2016-07-25T21:17:06Z

From: Scott Bauer <sbauer@plzdonthack.me>

commit 93a2001bdfd5376c3dc2158653034c20392d15c5 upstream.

This patch validates the num_values parameter from userland during the
HIDIOCGUSAGES and HIDIOCSUSAGES commands. Previously, if the report id was set
to HID_REPORT_ID_UNKNOWN, we would fail to validate the num_values parameter
leading to a heap overflow.

Signed-off-by: Scott Bauer <sbauer@plzdonthack.me>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hid/usbhid/hiddev.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/hid/usbhid/hiddev.c
+++ b/drivers/hid/usbhid/hiddev.c
@@ -516,13 +516,13 @@ static noinline int hiddev_ioctl_usage(s
goto inval;
} else if (uref->usage_index >= field->report_count)
goto inval;
-
- else if ((cmd == HIDIOCGUSAGES || cmd == HIDIOCSUSAGES) &&
- (uref_multi->num_values > HID_MAX_MULTI_USAGES ||
- uref->usage_index + uref_multi->num_values > field->report_count))
- goto inval;
}

+ if ((cmd == HIDIOCGUSAGES || cmd == HIDIOCSUSAGES) &&
+ (uref_multi->num_values > HID_MAX_MULTI_USAGES ||
+ uref->usage_index + uref_multi->num_values > field->report_count))
+ goto inval;
+
switch (cmd) {
case HIDIOCGUSAGE:
uref->value = field->value[uref->usage_index];