* [PATCH] ip6mr: Fix potential Spectre v1 vulnerability
@ 2018-12-11 20:10 Gustavo A. R. Silva
2018-12-14 23:35 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2018-12-11 20:10 UTC (permalink / raw)
To: David S. Miller, Alexey Kuznetsov, Hideaki YOSHIFUJI
Cc: netdev, linux-kernel, Gustavo A. R. Silva
vr.mifi is 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:
net/ipv6/ip6mr.c:1845 ip6mr_ioctl() warn: potential spectre issue 'mrt->vif_table' [r] (local cap)
net/ipv6/ip6mr.c:1919 ip6mr_compat_ioctl() warn: potential spectre issue 'mrt->vif_table' [r] (local cap)
Fix this by sanitizing vr.mifi before using it to index mrt->vif_table'
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
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
net/ipv6/ip6mr.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 8c63494400c4..5562cd7f6f56 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -52,6 +52,8 @@
#include <net/ip6_checksum.h>
#include <linux/netconf.h>
+#include <linux/nospec.h>
+
struct ip6mr_rule {
struct fib_rule common;
};
@@ -1841,6 +1843,7 @@ int ip6mr_ioctl(struct sock *sk, int cmd, void __user *arg)
return -EFAULT;
if (vr.mifi >= mrt->maxvif)
return -EINVAL;
+ vr.mifi = array_index_nospec(vr.mifi, mrt->maxvif);
read_lock(&mrt_lock);
vif = &mrt->vif_table[vr.mifi];
if (VIF_EXISTS(mrt, vr.mifi)) {
@@ -1915,6 +1918,7 @@ int ip6mr_compat_ioctl(struct sock *sk, unsigned int cmd, void __user *arg)
return -EFAULT;
if (vr.mifi >= mrt->maxvif)
return -EINVAL;
+ vr.mifi = array_index_nospec(vr.mifi, mrt->maxvif);
read_lock(&mrt_lock);
vif = &mrt->vif_table[vr.mifi];
if (VIF_EXISTS(mrt, vr.mifi)) {
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ip6mr: Fix potential Spectre v1 vulnerability
2018-12-11 20:10 [PATCH] ip6mr: Fix potential Spectre v1 vulnerability Gustavo A. R. Silva
@ 2018-12-14 23:35 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2018-12-14 23:35 UTC (permalink / raw)
To: gustavo; +Cc: kuznet, yoshfuji, netdev, linux-kernel
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Tue, 11 Dec 2018 14:10:08 -0600
> vr.mifi is 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:
>
> net/ipv6/ip6mr.c:1845 ip6mr_ioctl() warn: potential spectre issue 'mrt->vif_table' [r] (local cap)
> net/ipv6/ip6mr.c:1919 ip6mr_compat_ioctl() warn: potential spectre issue 'mrt->vif_table' [r] (local cap)
>
> Fix this by sanitizing vr.mifi before using it to index mrt->vif_table'
>
> 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
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Applied and queued up for -stable.
^ permalink raw reply [flat|nested] 2+ messages in thread
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