HID: validate HID report id size
Kees Cook [Wed, 28 Aug 2013 20:29:55 +0000 (22:29 +0200)]
The "Report ID" field of a HID report is used to build indexes of
reports. The kernel's index of these is limited to 256 entries, so any
malicious device that sets a Report ID greater than 255 will trigger
memory corruption on the host:

[ 1347.156239] BUG: unable to handle kernel paging request at ffff88094958a878
[ 1347.156261] IP: [<ffffffff813e4da0>] hid_register_report+0x2a/0x8b

CVE-2013-2888

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@kernel.org
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-core.c
include/linux/hid.h

index 264f550..95a97a4 100644 (file)
@@ -63,6 +63,8 @@ struct hid_report *hid_register_report(struct hid_device *device, unsigned type,
        struct hid_report_enum *report_enum = device->report_enum + type;
        struct hid_report *report;
 
+       if (id >= HID_MAX_IDS)
+               return NULL;
        if (report_enum->report_id_hash[id])
                return report_enum->report_id_hash[id];
 
@@ -404,8 +406,10 @@ static int hid_parser_global(struct hid_parser *parser, struct hid_item *item)
 
        case HID_GLOBAL_ITEM_TAG_REPORT_ID:
                parser->global.report_id = item_udata(item);
-               if (parser->global.report_id == 0) {
-                       hid_err(parser->device, "report_id 0 is invalid\n");
+               if (parser->global.report_id == 0 ||
+                   parser->global.report_id >= HID_MAX_IDS) {
+                       hid_err(parser->device, "report_id %u is invalid\n",
+                               parser->global.report_id);
                        return -1;
                }
                return 0;
@@ -575,7 +579,7 @@ static void hid_close_report(struct hid_device *device)
        for (i = 0; i < HID_REPORT_TYPES; i++) {
                struct hid_report_enum *report_enum = device->report_enum + i;
 
-               for (j = 0; j < 256; j++) {
+               for (j = 0; j < HID_MAX_IDS; j++) {
                        struct hid_report *report = report_enum->report_id_hash[j];
                        if (report)
                                hid_free_report(report);
index 8136c6d..95b6ddf 100644 (file)
@@ -393,10 +393,12 @@ struct hid_report {
        struct hid_device *device;                      /* associated device */
 };
 
+#define HID_MAX_IDS 256
+
 struct hid_report_enum {
        unsigned numbered;
        struct list_head report_list;
-       struct hid_report *report_id_hash[256];
+       struct hid_report *report_id_hash[HID_MAX_IDS];
 };
 
 #define HID_REPORT_TYPES 3