[kvm-unit-tests Patch 5/5] x86: pmu: Add asserts to warn inconsistent fixed events and counters

Dapeng Mi
2023-10-24T07:52:02Z

Current PMU code deosn't check whether PMU fixed counter number is
larger than pre-defined fixed events. If so, it would cause memory
access out of range.

So add assert to warn this invalid case.

Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
---
x86/pmu.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/x86/pmu.c b/x86/pmu.c
index 41165e168d8e..a1d615fbab3d 100644
--- a/x86/pmu.c
+++ b/x86/pmu.c
@@ -112,8 +112,12 @@ static struct pmu_event* get_counter_event(pmu_counter_t *cnt)
for (i = 0; i < gp_events_size; i++)
if (gp_events[i].unit_sel == (cnt->config & 0xffff))
return &gp_events[i];
- } else
- return &fixed_events[cnt->ctr - MSR_CORE_PERF_FIXED_CTR0];
+ } else {
+ int idx = cnt->ctr - MSR_CORE_PERF_FIXED_CTR0;
+
+ assert(idx < ARRAY_SIZE(fixed_events));
+ return &fixed_events[idx];
+ }

return (void*)0;
}
@@ -246,6 +250,7 @@ static void check_fixed_counters(void)
};
int i;

+ assert(pmu.nr_fixed_counters <= ARRAY_SIZE(fixed_events));
for (i = 0; i < pmu.nr_fixed_counters; i++) {
cnt.ctr = fixed_events[i].unit_sel;
measure_one(&cnt);
@@ -267,6 +272,7 @@ static void check_counters_many(void)
gp_events[i % gp_events_size].unit_sel;
n++;
}
+ assert(pmu.nr_fixed_counters <= ARRAY_SIZE(fixed_events));
for (i = 0; i < pmu.nr_fixed_counters; i++) {
cnt[n].ctr = fixed_events[i].unit_sel;
cnt[n].config = EVNTSEL_OS | EVNTSEL_USR;
--
2.34.1