From 5edbd2d8db426d49bc570a3a019720b5e810d951 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 20 Apr 2018 14:23:36 +0200 Subject: [PATCH] perf/x86/msr: Fix possible Spectre-v1 indexing in the MSR driver commit 06ce6e9b6d6c09d4129c6e24a1314a395d816c10 upstream. > arch/x86/events/msr.c:178 msr_event_init() warn: potential spectre issue 'msr' (local cap) Userspace controls @attr, sanitize cfg (attr->config) before using it to index an array. Reported-by: Dan Carpenter Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/events/msr.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/events/msr.c b/arch/x86/events/msr.c index 4bb3ec69e8ea..be0b1968d60a 100644 --- a/arch/x86/events/msr.c +++ b/arch/x86/events/msr.c @@ -1,4 +1,5 @@ #include +#include #include enum perf_msr_id { @@ -136,9 +137,6 @@ static int msr_event_init(struct perf_event *event) if (event->attr.type != event->pmu->type) return -ENOENT; - if (cfg >= PERF_MSR_EVENT_MAX) - return -EINVAL; - /* unsupported modes and filters */ if (event->attr.exclude_user || event->attr.exclude_kernel || @@ -149,6 +147,11 @@ static int msr_event_init(struct perf_event *event) event->attr.sample_period) /* no sampling */ return -EINVAL; + if (cfg >= PERF_MSR_EVENT_MAX) + return -EINVAL; + + cfg = array_index_nospec((unsigned long)cfg, PERF_MSR_EVENT_MAX); + if (!msr[cfg].attr) return -EINVAL; -- 2.20.1