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Message-ID: <20180731142557.GA12460@pjb1027-Latitude-E5410>
Date: Tue, 31 Jul 2018 23:25:57 +0900
From: Jinbum Park <jinb.park7@...il.com>
To: peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
alexander.shishkin@...ux.intel.com, jolsa@...hat.com,
namhyung@...nel.org
Cc: linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com
Subject: [PATCH] perf/core: Fix possible Spectre-v1 for perf_swevent_enabled
User controls @event_id which to be used as index of perf_swevent_enabled.
So, It can be exploited via Spectre-like attack. (speculative execution)
So sanitize @event_id before using it to prevent attack.
I leveraged strategy [1] to find 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>
---
kernel/events/core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index f6ea33a..3313552 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -50,6 +50,7 @@
#include <linux/sched/mm.h>
#include <linux/proc_ns.h>
#include <linux/mount.h>
+#include <linux/nospec.h>
#include "internal.h"
@@ -8200,6 +8201,7 @@ static int perf_swevent_init(struct perf_event *event)
if (err)
return err;
+ event_id = array_index_nospec(event_id, PERF_COUNT_SW_MAX);
static_key_slow_inc(&perf_swevent_enabled[event_id]);
event->destroy = sw_perf_event_destroy;
}
--
1.9.1
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