From efa61c8cf2950ab5c0e66cff3cabe2a2b24e81ba Mon Sep 17 00:00:00 2001
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Tue, 16 Oct 2018 15:06:41 +0200
Subject: [PATCH] ptp: fix Spectre v1 vulnerability
Git-commit: efa61c8cf2950ab5c0e66cff3cabe2a2b24e81ba
Patch-mainline: v4.19
References: bsc#1051510
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>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
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 01b0e2bb3319..2012551d93e0 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);
--
2.19.1