drivers/perf: hisi_pcie: Fix out-of-bound access when valid event group

The perf tool allows users to create event groups through following
cmd [1], but the driver does not check whether the array index is out of
bounds when writing data to the event_group array. If the number of events
in an event_group is greater than HISI_PCIE_MAX_COUNTERS, the memory write
overflow of event_group array occurs.

Add array index check to fix the possible array out of bounds violation,
and return directly when write new events are written to array bounds.

There are 9 different events in an event_group.
[1] perf stat -e '{pmu/event1/, ... ,pmu/event9/}'

Fixes: 8404b0fbc7fb ("drivers/perf: hisi: Add driver for HiSilicon PCIe PMU")
Signed-off-by: Junhao He <hejunhao3@huawei.com>
Reviewed-by: Jijie Shao <shaojijie@huawei.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20240425124627.13764-2-hejunhao3@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/perf/hisilicon/hisi_pcie_pmu.c b/drivers/perf/hisilicon/hisi_pcie_pmu.c
index b1e4739fbdb0a9d61fe7eaacf1b52bec8f8b1bfa..03c506aa385388ed88f596604c09e9bc4af23905 100644 (file)
--- a/drivers/perf/hisilicon/hisi_pcie_pmu.c
+++ b/drivers/perf/hisilicon/hisi_pcie_pmu.c
@@ -350,15 +350,27 @@ static bool hisi_pcie_pmu_validate_event_group(struct perf_event *event)
                        return false;
 
                for (num = 0; num < counters; num++) {
+                       /*
+                        * If we find a related event, then it's a valid group
+                        * since we don't need to allocate a new counter for it.
+                        */
                        if (hisi_pcie_pmu_cmp_event(event_group[num], sibling))
                                break;
                }
 
+               /*
+                * Otherwise it's a new event but if there's no available counter,
+                * fail the check since we cannot schedule all the events in
+                * the group simultaneously.
+                */
+               if (num == HISI_PCIE_MAX_COUNTERS)
+                       return false;
+
                if (num == counters)
                        event_group[counters++] = sibling;
        }
 
-       return counters <= HISI_PCIE_MAX_COUNTERS;
+       return true;
 }
 
 static int hisi_pcie_pmu_event_init(struct perf_event *event)