* [PATCH] ptp: fix Spectre v1 vulnerability
@ 2018-10-16 13:06 Gustavo A. R. Silva
2018-10-16 15:15 ` Richard Cochran
2018-10-18 5:02 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2018-10-16 13:06 UTC (permalink / raw)
To: Richard Cochran, David S. Miller
Cc: netdev, linux-kernel, Gustavo A. R. Silva
pin_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/ptp/ptp_chardev.c:253 ptp_ioctl() warn: potential spectre issue
'ops->pin_config' [r] (local cap)
Fix this by sanitizing pin_index before using it to index
ops->pin_config, and before passing it as an argument to
function ptp_set_pinfunc(), in which it is used to index
info->pin_config.
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/ptp/ptp_chardev.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 01b0e2b..2012551 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -24,6 +24,8 @@
#include <linux/slab.h>
#include <linux/timekeeping.h>
+#include <linux/nospec.h>
+
#include "ptp_private.h"
static int ptp_disable_pinfunc(struct ptp_clock_info *ops,
@@ -248,6 +250,7 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
err = -EINVAL;
break;
}
+ pin_index = array_index_nospec(pin_index, ops->n_pins);
if (mutex_lock_interruptible(&ptp->pincfg_mux))
return -ERESTARTSYS;
pd = ops->pin_config[pin_index];
@@ -266,6 +269,7 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
err = -EINVAL;
break;
}
+ pin_index = array_index_nospec(pin_index, ops->n_pins);
if (mutex_lock_interruptible(&ptp->pincfg_mux))
return -ERESTARTSYS;
err = ptp_set_pinfunc(ptp, pin_index, pd.func, pd.chan);
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] ptp: fix Spectre v1 vulnerability
2018-10-16 13:06 [PATCH] ptp: fix Spectre v1 vulnerability Gustavo A. R. Silva
@ 2018-10-16 15:15 ` Richard Cochran
2018-10-18 5:02 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Richard Cochran @ 2018-10-16 15:15 UTC (permalink / raw)
To: Gustavo A. R. Silva; +Cc: David S. Miller, netdev, linux-kernel
On Tue, Oct 16, 2018 at 03:06:41PM +0200, Gustavo A. R. Silva wrote:
> pin_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/ptp/ptp_chardev.c:253 ptp_ioctl() warn: potential spectre issue
> 'ops->pin_config' [r] (local cap)
>
> Fix this by sanitizing pin_index before using it to index
> ops->pin_config, and before passing it as an argument to
> function ptp_set_pinfunc(), in which it is used to index
> info->pin_config.
Acked-by: Richard Cochran <richardcochran@gmail.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] ptp: fix Spectre v1 vulnerability
2018-10-16 13:06 [PATCH] ptp: fix Spectre v1 vulnerability Gustavo A. R. Silva
2018-10-16 15:15 ` Richard Cochran
@ 2018-10-18 5:02 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2018-10-18 5:02 UTC (permalink / raw)
To: gustavo; +Cc: richardcochran, netdev, linux-kernel
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Tue, 16 Oct 2018 15:06:41 +0200
> pin_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/ptp/ptp_chardev.c:253 ptp_ioctl() warn: potential spectre issue
> 'ops->pin_config' [r] (local cap)
>
> Fix this by sanitizing pin_index before using it to index
> ops->pin_config, and before passing it as an argument to
> function ptp_set_pinfunc(), in which it is used to index
> info->pin_config.
>
> 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>
Applied.
^ permalink raw reply [flat|nested] 3+ messages in thread
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