[PATCH] perf/x86/intel: fix integer overflow when shifting 32 places

From	Colin King <colin.king@canonical.com>
Newsgroups	linux.kernel
Subject	[PATCH] perf/x86/intel: fix integer overflow when shifting 32 places
Date	2017-01-11 12:50 +0100
Message-ID	<sYpzH-6oe-11@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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From: Colin Ian King <colin.king@canonical.com>

When x86_pmu.num_counters is set to INTEL_PMC_MAX_GENERIC we end up
with the 32 bit integer constant 1 being shifted 32 places leading to
undefined behaviour.  Fix this by shifting 1ULL instead of 1.

Fixes CoverityScan CID#1192105 ("Bad bit shift operation")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 arch/x86/events/intel/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 8613826..d611cab 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3987,7 +3987,7 @@ __init int intel_pmu_init(void)
 		     x86_pmu.num_counters, INTEL_PMC_MAX_GENERIC);
 		x86_pmu.num_counters = INTEL_PMC_MAX_GENERIC;
 	}
-	x86_pmu.intel_ctrl = (1 << x86_pmu.num_counters) - 1;
+	x86_pmu.intel_ctrl = (1ULL << x86_pmu.num_counters) - 1;
 
 	if (x86_pmu.num_counters_fixed > INTEL_PMC_MAX_FIXED) {
 		WARN(1, KERN_ERR "hw perf events fixed %d > max(%d), clipping!",
-- 
2.10.2

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[PATCH] perf/x86/intel: fix integer overflow when shifting 32 places Colin King <colin.king@canonical.com> - 2017-01-11 12:50 +0100
  [tip:perf/urgent] perf/x86/intel: Use ULL constant to prevent  undefined shift behaviour tip-bot for Colin King <tipbot@zytor.com> - 2017-01-11 16:50 +0100

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