From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Fri, 21 Dec 2018 15:41:17 -0600
Subject: phonet: af_phonet: Fix Spectre v1 vulnerability
Git-commit: d686026b1e6ed4ea27d630d8f54f9a694db088b2
Patch-mainline: v5.0-rc1
References: networking-stable-19_01_04
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
net/phonet/af_phonet.c | 3 +++
1 file changed, 3 insertions(+)
--- 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 struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
@@ -43,6 +45,7 @@ static struct phonet_protocol *phonet_pr
if (protocol >= PHONET_NPROTO)
return NULL;
+ protocol = array_index_nospec(protocol, PHONET_NPROTO);
rcu_read_lock();
pp = rcu_dereference(proto_tab[protocol]);