From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Thu, 3 May 2018 13:17:12 -0500
Subject: atm: zatm: Fix potential Spectre v1
Git-commit: 2be147f7459db5bbf292e0a6f135037b55e20b39
Patch-mainline: v4.17-rc5
References: networking-stable-18_05_15 bsc#1068032 CVE-2017-5753
pool 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/atm/zatm.c:1462 zatm_ioctl() warn: potential spectre issue
'zatm_dev->pool_info' (local cap)
Fix this by sanitizing pool before using it to index
zatm_dev->pool_info
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: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/atm/zatm.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/atm/zatm.c b/drivers/atm/zatm.c
index 1ef67db03c8e..9c9a22958717 100644
--- a/drivers/atm/zatm.c
+++ b/drivers/atm/zatm.c
@@ -28,6 +28,7 @@
#include <asm/io.h>
#include <linux/atomic.h>
#include <linux/uaccess.h>
+#include <linux/nospec.h>
#include "uPD98401.h"
#include "uPD98402.h"
@@ -1458,6 +1459,8 @@ static int zatm_ioctl(struct atm_dev *dev,unsigned int cmd,void __user *arg)
return -EFAULT;
if (pool < 0 || pool > ZATM_LAST_POOL)
return -EINVAL;
+ pool = array_index_nospec(pool,
+ ZATM_LAST_POOL + 1);
spin_lock_irqsave(&zatm_dev->lock, flags);
info = zatm_dev->pool_info[pool];
if (cmd == ZATM_GETPOOLZ) {
--
2.18.0