perf/x86: Fix potential out-of-bounds access

UBSAN reported out-of-bound accesses for x86_pmu.event_map(), it's
arguments should be < x86_pmu.max_events. Make sure all users observe
this constraint.

Reported-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Meelis Roos <mroos@linux.ee>

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 9a89d98..84fe1be 100644 (file)
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1642,9 +1642,12 @@ static struct attribute_group x86_pmu_format_group __ro_after_init = {
 
 ssize_t events_sysfs_show(struct device *dev, struct device_attribute *attr, char *page)
 {
-       struct perf_pmu_events_attr *pmu_attr = \
+       struct perf_pmu_events_attr *pmu_attr =
                container_of(attr, struct perf_pmu_events_attr, attr);
-       u64 config = x86_pmu.event_map(pmu_attr->id);
+       u64 config = 0;
+
+       if (pmu_attr->id < x86_pmu.max_events)
+               config = x86_pmu.event_map(pmu_attr->id);
 
        /* string trumps id */
        if (pmu_attr->event_str)
@@ -1713,6 +1716,9 @@ is_visible(struct kobject *kobj, struct attribute *attr, int idx)
 {
        struct perf_pmu_events_attr *pmu_attr;
 
+       if (idx >= x86_pmu.max_events)
+               return 0;
+
        pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr.attr);
        /* str trumps id */
        return pmu_attr->event_str || x86_pmu.event_map(idx) ? attr->mode : 0;