* [PATCH] perf/x86/intel: fix integer overflow when shifting 32 places
@ 2017-01-11 11:43 Colin King
2017-01-11 15:46 ` [tip:perf/urgent] perf/x86/intel: Use ULL constant to prevent undefined shift behaviour tip-bot for Colin King
0 siblings, 1 reply; 2+ messages in thread
From: Colin King @ 2017-01-11 11:43 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, H . Peter Anvin, x86,
Peter Zijlstra, Andi Kleen, Stephane Eranian, Kan Liang,
Alexander Shishkin
Cc: linux-kernel
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [tip:perf/urgent] perf/x86/intel: Use ULL constant to prevent undefined shift behaviour
2017-01-11 11:43 [PATCH] perf/x86/intel: fix integer overflow when shifting 32 places Colin King
@ 2017-01-11 15:46 ` tip-bot for Colin King
0 siblings, 0 replies; 2+ messages in thread
From: tip-bot for Colin King @ 2017-01-11 15:46 UTC (permalink / raw)
To: linux-tip-commits
Cc: tglx, colin.king, mingo, peterz, kan.liang, linux-kernel,
alexander.shishkin, ak, eranian, hpa
Commit-ID: ad5013d5699d30ded0cdbbc68b93b2aa28222c6e
Gitweb: http://git.kernel.org/tip/ad5013d5699d30ded0cdbbc68b93b2aa28222c6e
Author: Colin King <colin.king@canonical.com>
AuthorDate: Wed, 11 Jan 2017 11:43:10 +0000
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 11 Jan 2017 16:43:30 +0100
perf/x86/intel: Use ULL constant to prevent undefined shift behaviour
When x86_pmu.num_counters is 32 the shift of the integer constant 1 is
exceeding 32bit and therefor undefined behaviour.
Fix this by shifting 1ULL instead of 1.
Reported-by: CoverityScan CID#1192105 ("Bad bit shift operation")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Link: http://lkml.kernel.org/r/20170111114310.17928-1-colin.king@canonical.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
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!",
^ permalink raw reply related [flat|nested] 2+ messages in thread
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