Commit 3a2af7cc authored Jul 31, 2018 by Jinbum Park Committed by Johannes Berg Aug 28, 2018

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@gmail.com>
[johannes: unwrap URL]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

parent 20932750

drivers/net/wireless/mac80211_hwsim.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -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];
		}

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