* [PATCH] phonet: af_phonet: Fix Spectre v1 vulnerability
@ 2018-12-21 21:41 Gustavo A. R. Silva
2018-12-22 9:35 ` Rémi Denis-Courmont
2018-12-22 23:08 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2018-12-21 21:41 UTC (permalink / raw)
To: Remi Denis-Courmont, David S. Miller
Cc: netdev, linux-kernel, Gustavo A. R. Silva
protocol 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/phonet/af_phonet.c:48 phonet_proto_get() warn: potential spectre issue 'proto_tab' [w] (local cap)
Fix this by sanitizing protocol before using it to index proto_tab.
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/phonet/af_phonet.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/phonet/af_phonet.c b/net/phonet/af_phonet.c
index 3b0ef691f5b1..d4b2abd78858 100644
--- a/net/phonet/af_phonet.c
+++ b/net/phonet/af_phonet.c
@@ -34,6 +34,8 @@
#include <net/phonet/phonet.h>
#include <net/phonet/pn_dev.h>
+#include <linux/nospec.h>
+
/* Transport protocol registration */
static const struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
@@ -43,6 +45,7 @@ static const struct phonet_protocol *phonet_proto_get(unsigned int protocol)
if (protocol >= PHONET_NPROTO)
return NULL;
+ protocol = array_index_nospec(protocol, PHONET_NPROTO);
rcu_read_lock();
pp = rcu_dereference(proto_tab[protocol]);
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] phonet: af_phonet: Fix Spectre v1 vulnerability
2018-12-21 21:41 [PATCH] phonet: af_phonet: Fix Spectre v1 vulnerability Gustavo A. R. Silva
@ 2018-12-22 9:35 ` Rémi Denis-Courmont
2018-12-22 23:08 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Rémi Denis-Courmont @ 2018-12-22 9:35 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Remi Denis-Courmont, David S. Miller, netdev, linux-kernel
Le vendredi 21 décembre 2018, 23:41:17 EET Gustavo A. R. Silva a écrit :
> protocol is indirectly controlled by user-space, hence leading to
> a potential exploitation of the Spectre variant 1 vulnerability.
No objections but AFAIR, only privileged userspace can trigger that code so
the impact is kinda limited.
--
Rémi Denis-Courmont
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] phonet: af_phonet: Fix Spectre v1 vulnerability
2018-12-21 21:41 [PATCH] phonet: af_phonet: Fix Spectre v1 vulnerability Gustavo A. R. Silva
2018-12-22 9:35 ` Rémi Denis-Courmont
@ 2018-12-22 23:08 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2018-12-22 23:08 UTC (permalink / raw)
To: gustavo; +Cc: courmisch, netdev, linux-kernel
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Fri, 21 Dec 2018 15:41:17 -0600
> protocol 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/phonet/af_phonet.c:48 phonet_proto_get() warn: potential spectre issue 'proto_tab' [w] (local cap)
>
> Fix this by sanitizing protocol before using it to index proto_tab.
>
> 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, thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-12-22 9:35 ` Rémi Denis-Courmont
2018-12-22 23:08 ` David Miller
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