From: Kees Cook <keesc...@chromium.org>
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 <keesc...@chromium.org>
Cc: sta...@kernel.org
---
drivers/hid/hid-core.c | 10 +++++++---
include/linux/hid.h | 4 +++-
2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 36668d1..5ea7d51 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -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);
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 0c48991..ff545cc 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -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
--
Jiri Kosina
SUSE Labs
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