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Date: Tue, 31 Jul 2018 23:10:40 +0900
From: Jinbum Park <jinb.park7@...il.com>
To: johannes@...solutions.net, kvalo@...eaurora.org, davem@...emloft.net
Cc: linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com
Subject: [PATCH] mac80211_hwsim: Fix possible Spectre-v1 for
hwsim_world_regdom_custom
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@...il.com>
---
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 998dfac..b41fdc3 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -34,6 +34,7 @@
#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
@@ -3350,6 +3351,9 @@ 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];
}
--
1.9.1
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