[PATCH 1/3] drivers/perf: hisi_pcie: Fix out-of-bound access when valid event group

[Jijie Shao]

Reviewed-by: Jijie Shao<shaojijie at huawei.com>

on 2024/4/25 20:46, Junhao He wrote:
> 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 at huawei.com>
> ---
>   drivers/perf/hisilicon/hisi_pcie_pmu.c | 14 +++++++++++++-
>   1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/perf/hisilicon/hisi_pcie_pmu.c b/drivers/perf/hisilicon/hisi_pcie_pmu.c
> index 5d1f0e9fdb08..dba399125658 100644
> --- 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)