lkml.org 
[lkml]   [2018]   [Jul]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] perf/core: fix possible spectre-v1 write
Date
It's possible for userspace to control event_id. Sanitize event_id when
using it as an array index, to inhibit the potential spectre-v1 write
gadget.

This class of issue is also known as CVE-2018-3693, or "bounds check bypass
store".

Found by smatch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
---
kernel/events/core.c | 2 ++
1 file changed, 2 insertions(+)

For Arm CPUs, more details can be found in the Arm Cache Speculation
Side-channels whitepaper, available from the Arm security updates site [1].

Mark.

[1] https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 8f0434a9951a..eece719bd18e 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8155,6 +8155,7 @@ struct static_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
static void sw_perf_event_destroy(struct perf_event *event)
{
u64 event_id = event->attr.config;
+ event_id = array_index_nospec(event_id, PERF_COUNT_SW_MAX);

WARN_ON(event->parent);

@@ -8186,6 +8187,7 @@ static int perf_swevent_init(struct perf_event *event)

if (event_id >= PERF_COUNT_SW_MAX)
return -ENOENT;
+ event_id = array_index_nospec(event_id, PERF_COUNT_SW_MAX);

if (!event->parent) {
int err;
--
2.11.0
\
 
 \ /
  Last update: 2018-07-10 20:24    [W:0.048 / U:1.204 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site