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Subject: Re: [PATCH] perf auxtrace: Fix potential null pointer dereference
To:     Leo Yan <leo.yan@linaro.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Andi Kleen <ak@linux.intel.com>,
        Tiezhu Yang <yangtiezhu@loongson.cn>,
        linux-kernel@vger.kernel.org
References: <20210420151554.2031768-1-leo.yan@linaro.org>
From:   Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
 Business Identity Code: 0357606 - 4, Domiciled in Helsinki
Message-ID: <22a1f6b4-0e4f-72df-2873-b4098a6c73dc@intel.com>
Date:   Tue, 20 Apr 2021 18:51:06 +0300
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On 20/04/21 6:15 pm, Leo Yan wrote:
> In the function auxtrace_parse_snapshot_options(), the callback pointer
> "itr->parse_snapshot_options" can be NULL if it has not been set during
> the AUX record initialization.  This can cause tool crashing if the
> callback pointer "itr->parse_snapshot_options" is dereferenced without
> performing NULL check.
> 
> Add a NULL check for the pointer "itr->parse_snapshot_options" before
> invoke the callback.
> 
> Fixes: d20031bb63dd ("perf tools: Add AUX area tracing Snapshot Mode")
> Signed-off-by: Leo Yan <leo.yan@linaro.org>

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
>  tools/perf/util/auxtrace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
> index 953f4afacd3b..320b47f133d3 100644
> --- a/tools/perf/util/auxtrace.c
> +++ b/tools/perf/util/auxtrace.c
> @@ -638,7 +638,7 @@ int auxtrace_parse_snapshot_options(struct auxtrace_record *itr,
>  		break;
>  	}
>  
> -	if (itr)
> +	if (itr && itr->parse_snapshot_options)
>  		return itr->parse_snapshot_options(itr, opts, str);
>  
>  	pr_err("No AUX area tracing to snapshot\n");
>