From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:60304 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731232AbeKLIYm (ORCPT ); Mon, 12 Nov 2018 03:24:42 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Breno Leitao , Jiri Kosina Subject: [PATCH 4.9 091/141] HID: hiddev: fix potential Spectre v1 Date: Sun, 11 Nov 2018 14:25:50 -0800 Message-Id: <20181111221640.779038211@linuxfoundation.org> In-Reply-To: <20181111221627.853046496@linuxfoundation.org> References: <20181111221627.853046496@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Breno Leitao commit f11274396a538b31bc010f782e05c2ce3f804c13 upstream. uref->usage_index can be indirectly controlled by userspace, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This field is used as an array index by the hiddev_ioctl_usage() function, when 'cmd' is either HIDIOCGCOLLECTIONINDEX, HIDIOCGUSAGES or HIDIOCSUSAGES. For cmd == HIDIOCGCOLLECTIONINDEX case, uref->usage_index is compared to field->maxusage and then used as an index to dereference field->usage array. The same thing happens to the cmd == HIDIOC{G,S}USAGES cases, where uref->usage_index is checked against an array maximum value and then it is used as an index in an array. This is a summary of the HIDIOCGCOLLECTIONINDEX case, which matches the traditional Spectre V1 first load: copy_from_user(uref, user_arg, sizeof(*uref)) if (uref->usage_index >= field->maxusage) goto inval; i = field->usage[uref->usage_index].collection_index; return i; This patch fixes this by sanitizing field uref->usage_index before using it to index field->usage (HIDIOCGCOLLECTIONINDEX) or field->value in HIDIOC{G,S}USAGES arrays, thus, avoiding speculation in the first load. Cc: Signed-off-by: Breno Leitao v2: Contemplate cmd == HIDIOC{G,S}USAGES case Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman --- drivers/hid/usbhid/hiddev.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) --- a/drivers/hid/usbhid/hiddev.c +++ b/drivers/hid/usbhid/hiddev.c @@ -521,14 +521,24 @@ static noinline int hiddev_ioctl_usage(s if (cmd == HIDIOCGCOLLECTIONINDEX) { if (uref->usage_index >= field->maxusage) goto inval; + uref->usage_index = + array_index_nospec(uref->usage_index, + field->maxusage); } else if (uref->usage_index >= 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; + if (cmd == HIDIOCGUSAGES || cmd == HIDIOCSUSAGES) { + if (uref_multi->num_values > HID_MAX_MULTI_USAGES || + uref->usage_index + uref_multi->num_values > + field->report_count) + goto inval; + + uref->usage_index = + array_index_nospec(uref->usage_index, + field->report_count - + uref_multi->num_values); + } switch (cmd) { case HIDIOCGUSAGE: