* [PATCH] net: atm: Fix potential Spectre v1 vulnerabilities
@ 2019-04-15 20:57 Gustavo A. R. Silva
2019-04-17 4:02 ` David Miller
0 siblings, 1 reply; 3+ messages in thread
From: Gustavo A. R. Silva @ 2019-04-15 20:57 UTC (permalink / raw)
To: David S. Miller; +Cc: netdev, linux-kernel, Gustavo A. R. Silva
arg is 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/atm/lec.c:715 lec_mcast_attach() warn: potential spectre issue 'dev_lec' [r] (local cap)
Fix this by sanitizing arg before using it to index dev_lec.
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://lore.kernel.org/lkml/20180423164740.GY17484@dhcp22.suse.cz/
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
net/atm/lec.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/atm/lec.c b/net/atm/lec.c
index d7f5cf5b7594..ad4f829193f0 100644
--- a/net/atm/lec.c
+++ b/net/atm/lec.c
@@ -710,7 +710,10 @@ static int lec_vcc_attach(struct atm_vcc *vcc, void __user *arg)
static int lec_mcast_attach(struct atm_vcc *vcc, int arg)
{
- if (arg < 0 || arg >= MAX_LEC_ITF || !dev_lec[arg])
+ if (arg < 0 || arg >= MAX_LEC_ITF)
+ return -EINVAL;
+ arg = array_index_nospec(arg, MAX_LEC_ITF);
+ if (!dev_lec[arg])
return -EINVAL;
vcc->proto_data = dev_lec[arg];
return lec_mcast_make(netdev_priv(dev_lec[arg]), vcc);
@@ -728,6 +731,7 @@ static int lecd_attach(struct atm_vcc *vcc, int arg)
i = arg;
if (arg >= MAX_LEC_ITF)
return -EINVAL;
+ i = array_index_nospec(arg, MAX_LEC_ITF);
if (!dev_lec[i]) {
int size;
--
2.21.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] net: atm: Fix potential Spectre v1 vulnerabilities
2019-04-15 20:57 [PATCH] net: atm: Fix potential Spectre v1 vulnerabilities Gustavo A. R. Silva
@ 2019-04-17 4:02 ` David Miller
2019-04-17 4:05 ` Gustavo A. R. Silva
0 siblings, 1 reply; 3+ messages in thread
From: David Miller @ 2019-04-17 4:02 UTC (permalink / raw)
To: gustavo; +Cc: netdev, linux-kernel
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Mon, 15 Apr 2019 15:57:23 -0500
> arg is 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/atm/lec.c:715 lec_mcast_attach() warn: potential spectre issue 'dev_lec' [r] (local cap)
>
> Fix this by sanitizing arg before using it to index dev_lec.
>
> 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://lore.kernel.org/lkml/20180423164740.GY17484@dhcp22.suse.cz/
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Applied and queued up for -stable.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] net: atm: Fix potential Spectre v1 vulnerabilities
2019-04-17 4:02 ` David Miller
@ 2019-04-17 4:05 ` Gustavo A. R. Silva
0 siblings, 0 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2019-04-17 4:05 UTC (permalink / raw)
To: David Miller; +Cc: netdev, linux-kernel
On 4/16/19 11:02 PM, David Miller wrote:
> From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
> Date: Mon, 15 Apr 2019 15:57:23 -0500
>
>> arg is 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/atm/lec.c:715 lec_mcast_attach() warn: potential spectre issue 'dev_lec' [r] (local cap)
>>
>> Fix this by sanitizing arg before using it to index dev_lec.
>>
>> 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://lore.kernel.org/lkml/20180423164740.GY17484@dhcp22.suse.cz/
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>
> Applied and queued up for -stable.
>
Thank you, Dave.
--
Gustavo
^ permalink raw reply [flat|nested] 3+ messages in thread
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