* [PATCH] ipv4: Fix potential Spectre v1 vulnerability
@ 2018-12-10 18:41 Gustavo A. R. Silva
2018-12-10 20:11 ` David Miller
0 siblings, 1 reply; 3+ messages in thread
From: Gustavo A. R. Silva @ 2018-12-10 18:41 UTC (permalink / raw)
To: David S. Miller, Alexey Kuznetsov, Hideaki YOSHIFUJI
Cc: netdev, linux-kernel, Gustavo A. R. Silva
vr.vifi 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/ipv4/ipmr.c:1616 ipmr_ioctl() warn: potential spectre issue 'mrt->vif_table' [r] (local cap)
net/ipv4/ipmr.c:1690 ipmr_compat_ioctl() warn: potential spectre issue 'mrt->vif_table' [r] (local cap)
Fix this by sanitizing vr.vifi 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
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
net/ipv4/ipmr.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index ea04e38f56e9..8c03fb05d3e6 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -69,6 +69,8 @@
#include <net/nexthop.h>
#include <net/switchdev.h>
+#include <linux/nospec.h>
+
struct ipmr_rule {
struct fib_rule common;
};
@@ -1612,6 +1614,7 @@ int ipmr_ioctl(struct sock *sk, int cmd, void __user *arg)
return -EFAULT;
if (vr.vifi >= mrt->maxvif)
return -EINVAL;
+ vr.vifi = array_index_nospec(vr.vifi, mrt->maxvif);
read_lock(&mrt_lock);
vif = &mrt->vif_table[vr.vifi];
if (VIF_EXISTS(mrt, vr.vifi)) {
@@ -1686,6 +1689,7 @@ int ipmr_compat_ioctl(struct sock *sk, unsigned int cmd, void __user *arg)
return -EFAULT;
if (vr.vifi >= mrt->maxvif)
return -EINVAL;
+ vr.vifi = array_index_nospec(vr.vifi, mrt->maxvif);
read_lock(&mrt_lock);
vif = &mrt->vif_table[vr.vifi];
if (VIF_EXISTS(mrt, vr.vifi)) {
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] ipv4: Fix potential Spectre v1 vulnerability
2018-12-10 18:41 [PATCH] ipv4: Fix potential Spectre v1 vulnerability Gustavo A. R. Silva
@ 2018-12-10 20:11 ` David Miller
2018-12-10 21:20 ` Gustavo A. R. Silva
0 siblings, 1 reply; 3+ messages in thread
From: David Miller @ 2018-12-10 20:11 UTC (permalink / raw)
To: gustavo; +Cc: kuznet, yoshfuji, netdev, linux-kernel
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Mon, 10 Dec 2018 12:41:24 -0600
> vr.vifi 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/ipv4/ipmr.c:1616 ipmr_ioctl() warn: potential spectre issue 'mrt->vif_table' [r] (local cap)
> net/ipv4/ipmr.c:1690 ipmr_compat_ioctl() warn: potential spectre issue 'mrt->vif_table' [r] (local cap)
>
> Fix this by sanitizing vr.vifi 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
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Applied and queued up for -stable.
Please do not CC: stable for networking bug fixes, thank you.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] ipv4: Fix potential Spectre v1 vulnerability
2018-12-10 20:11 ` David Miller
@ 2018-12-10 21:20 ` Gustavo A. R. Silva
0 siblings, 0 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2018-12-10 21:20 UTC (permalink / raw)
To: David Miller; +Cc: kuznet, yoshfuji, netdev, linux-kernel
On 12/10/18 2:11 PM, David Miller wrote:
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>
> Applied and queued up for -stable.
>
> Please do not CC: stable for networking bug fixes, thank you.
>
OK. I've got it.
Thanks
--
Gustavo
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-12-10 20:11 ` David Miller
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