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Date: Fri, 26 Apr 2024 16:41:29 +0100
From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: Junhao He <hejunhao3@huawei.com>
CC: <will@kernel.org>, <yangyicong@huawei.com>, <shaojijie@huawei.com>,
	<linux-kernel@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>,
	<linuxarm@huawei.com>, <prime.zeng@hisilicon.com>, <chenhao418@huawei.com>
Subject: Re: [PATCH 2/3] drivers/perf: hisi: hns3: Fix out-of-bound access
 when valid event group
Message-ID: <20240426164129.00004b37@Huawei.com>
In-Reply-To: <20240425124627.13764-3-hejunhao3@huawei.com>
References: <20240425124627.13764-1-hejunhao3@huawei.com>
	<20240425124627.13764-3-hejunhao3@huawei.com>
Organization: Huawei Technologies Research and Development (UK) Ltd.
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On Thu, 25 Apr 2024 20:46:26 +0800
Junhao He <hejunhao3@huawei.com> 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 HNS3_PMU_MAX_HW_EVENTS, 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: 66637ab137b4 ("drivers/perf: hisi: add driver for HNS3 PMU")
> Signed-off-by: Junhao He <hejunhao3@huawei.com>
> Signed-off-by: Hao Chen <chenhao418@huawei.com>

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  drivers/perf/hisilicon/hns3_pmu.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/perf/hisilicon/hns3_pmu.c b/drivers/perf/hisilicon/hns3_pmu.c
> index 16869bf5bf4c..cbdd53b0a034 100644
> --- a/drivers/perf/hisilicon/hns3_pmu.c
> +++ b/drivers/perf/hisilicon/hns3_pmu.c
> @@ -1085,15 +1085,27 @@ static bool hns3_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 (hns3_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 == HNS3_PMU_MAX_HW_EVENTS)
> +			return false;
> +
>  		if (num == counters)
>  			event_group[counters++] = sibling;
>  	}
>  
> -	return counters <= HNS3_PMU_MAX_HW_EVENTS;
> +	return true;
>  }
>  
>  static u32 hns3_pmu_get_filter_condition(struct perf_event *event)