HID: hiddev: validate num_values for HIDIOCGUSAGES, HIDIOCSUSAGES commands

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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c
index 4ef02b2..1378ae0 100644 (file)
--- a/drivers/hid/usbhid/hiddev.c
+++ b/drivers/hid/usbhid/hiddev.c
@@ -515,13 +515,13 @@ static noinline int hiddev_ioctl_usage(struct hiddev *hiddev, unsigned int cmd,
                                        goto inval;
                        } else if (uref->usage_index >= field->report_count)
                                goto inval;
                                        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];
                switch (cmd) {
                case HIDIOCGUSAGE:
                        uref->value = field->value[uref->usage_index];