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perf/x86/cstate: Fix possible Spectre-v1 indexing for pkg_msr 

> arch/x86/events/intel/cstate.c:307 cstate_pmu_event_init() warn: potential spectre issue 'pkg_msr' (local cap)

Userspace controls @attr, sanitize cfg (attr->config) before using it
to index an array.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2018-04-20 14:25:48 +02:00 committed by Ingo Molnar
parent 06ce6e9b6d
commit a5f81290ce
1 changed files with 2 additions and 0 deletions
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2
arch/x86/events/intel/cstate.c
View File

@ -92,6 +92,7 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/perf_event.h>
#include <linux/nospec.h>
#include <asm/cpu_device_id.h>
#include <asm/intel-family.h>
#include "../perf_event.h"
@ -302,6 +303,7 @@ static int cstate_pmu_event_init(struct perf_event *event)
} else if (event->pmu == &cstate_pkg_pmu) {
if (cfg >= PERF_CSTATE_PKG_EVENT_MAX)
return -EINVAL;
cfg = array_index_nospec((unsigned long)cfg, PERF_CSTATE_PKG_EVENT_MAX);
if (!pkg_msr[cfg].attr)
return -EINVAL;
event->hw.event_base = pkg_msr[cfg].msr;