* [PATCH] HID: hiddev: fix potential Spectre v1
@ 2018-06-29 22:08 Gustavo A. R. Silva
2018-07-09 12:31 ` Jiri Kosina
0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2018-06-29 22:08 UTC (permalink / raw)
To: Jiri Kosina, Benjamin Tissoires
Cc: linux-usb, linux-input, linux-kernel, Gustavo A. R. Silva
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>
---
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 e3ce233..23872d0 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;
--
2.7.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] HID: hiddev: fix potential Spectre v1
2018-06-29 22:08 [PATCH] HID: hiddev: fix potential Spectre v1 Gustavo A. R. Silva
@ 2018-07-09 12:31 ` Jiri Kosina
0 siblings, 0 replies; 2+ messages in thread
From: Jiri Kosina @ 2018-07-09 12:31 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Benjamin Tissoires, linux-usb, linux-input, linux-kernel
On Fri, 29 Jun 2018, Gustavo A. R. Silva wrote:
> 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:
Applied, thanks Gustavo.
--
Jiri Kosina
SUSE Labs
^ permalink raw reply [flat|nested] 2+ messages in thread
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