From 4f65245f2d178b9cba48350620d76faa4a098841 Mon Sep 17 00:00:00 2001
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Fri, 29 Jun 2018 17:08:44 -0500
Subject: [PATCH] HID: hiddev: fix potential Spectre v1
Git-commit: 4f65245f2d178b9cba48350620d76faa4a098841
Patch-mainline: v4.18-rc5
References: bsc#1051510
uref->field_index, uref->usage_index, finfo.field_index and cinfo.index can be
indirectly controlled by user-space, hence leading to a potential exploitation
of the Spectre variant 1 vulnerability.
This issue was detected with the help of Smatch:
drivers/hid/usbhid/hiddev.c:473 hiddev_ioctl_usage() warn: potential spectre issue 'report->field' (local cap)
drivers/hid/usbhid/hiddev.c:477 hiddev_ioctl_usage() warn: potential spectre issue 'field->usage' (local cap)
drivers/hid/usbhid/hiddev.c:757 hiddev_ioctl() warn: potential spectre issue 'report->field' (local cap)
drivers/hid/usbhid/hiddev.c:801 hiddev_ioctl() warn: potential spectre issue 'hid->collection' (local cap)
Fix this by sanitizing such structure fields before using them to index
report->field, field->usage and hid->collection
Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/hid/usbhid/hiddev.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c
index e3ce233f8bdc..23872d08308c 100644
--- a/drivers/hid/usbhid/hiddev.c
+++ b/drivers/hid/usbhid/hiddev.c
@@ -36,6 +36,7 @@
#include <linux/hiddev.h>
#include <linux/compat.h>
#include <linux/vmalloc.h>
+#include <linux/nospec.h>
#include "usbhid.h"
#ifdef CONFIG_USB_DYNAMIC_MINORS
@@ -469,10 +470,14 @@ static noinline int hiddev_ioctl_usage(struct hiddev *hiddev, unsigned int cmd,
if (uref->field_index >= report->maxfield)
goto inval;
+ uref->field_index = array_index_nospec(uref->field_index,
+ report->maxfield);
field = report->field[uref->field_index];
if (uref->usage_index >= field->maxusage)
goto inval;
+ uref->usage_index = array_index_nospec(uref->usage_index,
+ field->maxusage);
uref->usage_code = field->usage[uref->usage_index].hid;
@@ -499,6 +504,8 @@ static noinline int hiddev_ioctl_usage(struct hiddev *hiddev, unsigned int cmd,
if (uref->field_index >= report->maxfield)
goto inval;
+ uref->field_index = array_index_nospec(uref->field_index,
+ report->maxfield);
field = report->field[uref->field_index];
@@ -753,6 +760,8 @@ static long hiddev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
if (finfo.field_index >= report->maxfield)
break;
+ finfo.field_index = array_index_nospec(finfo.field_index,
+ report->maxfield);
field = report->field[finfo.field_index];
memset(&finfo, 0, sizeof(finfo));
@@ -797,6 +806,8 @@ static long hiddev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
if (cinfo.index >= hid->maxcollection)
break;
+ cinfo.index = array_index_nospec(cinfo.index,
+ hid->maxcollection);
cinfo.type = hid->collection[cinfo.index].type;
cinfo.usage = hid->collection[cinfo.index].usage;
--
2.18.0