From 3a2af7cccbbaf2362db9053a946a6084e12bfa73 Mon Sep 17 00:00:00 2001
From: Jinbum Park <jinb.park7@gmail.com>
Date: Tue, 31 Jul 2018 23:10:40 +0900
Subject: [PATCH] mac80211_hwsim: Fix possible Spectre-v1 for hwsim_world_regdom_custom
Git-commit: 3a2af7cccbbaf2362db9053a946a6084e12bfa73
Patch-mainline: v4.19-rc3
References: FATE#326294
User controls @idx which to be used as index of hwsim_world_regdom_custom.
So, It can be exploited via Spectre-like attack. (speculative execution)
This kind of attack leaks address of hwsim_world_regdom_custom,
It leads an attacker to bypass security mechanism such as KASLR.
So sanitize @idx before using it to prevent attack.
I leveraged strategy [1] to find and exploit this gadget.
[1] https://github.com/jinb-park/linux-exploit/tree/master/exploit-remaining-spectre-gadget/
Signed-off-by: Jinbum Park <jinb.park7@gmail.com>
[johannes: unwrap URL]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/net/wireless/mac80211_hwsim.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 7d0b460868f9..80e2c8595c7c 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -33,6 +33,7 @@
#include <net/net_namespace.h>
#include <net/netns/generic.h>
#include <linux/rhashtable.h>
+#include <linux/nospec.h>
#include "mac80211_hwsim.h"
#define WARN_QUEUE 100
@@ -3229,6 +3230,9 @@ static int hwsim_new_radio_nl(struct sk_buff *msg, struct genl_info *info)
kfree(hwname);
return -EINVAL;
}
+
+ idx = array_index_nospec(idx,
+ ARRAY_SIZE(hwsim_world_regdom_custom));
param.regd = hwsim_world_regdom_custom[idx];
}
--
2.19.2