linux-kernel - Re: [PATCH v2] perf session: fix decompression of PERF_RECORD

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Date:   Mon, 18 Nov 2019 17:20:31 +0300
From:   Alexey Budankov <alexey.budankov@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] perf session: fix decompression of
 PERF_RECORD_COMPRESSED records

On 18.11.2019 15:22, Jiri Olsa wrote:
> On Mon, Nov 18, 2019 at 02:30:04PM +0300, Alexey Budankov wrote:
<SNIP>
>>
>> @@ -1971,20 +1971,32 @@ fetch_mmaped_event(struct perf_session *session,
>>  		return NULL;
>>  
>>  	event = (union perf_event *)(buf + head);
>> +	if (needs_swap)
>> +		perf_event_header__bswap(&event->header);
>>  
>> -	if (session->header.needs_swap)
>> +	if (head + event->header.size <= mmap_size)
>> +		return event;
>> +
>> +	/* We're not fetching the event so swap back again */
>> +	if (needs_swap)
>>  		perf_event_header__bswap(&event->header);
>>  
>> -	if (head + event->header.size > mmap_size) {
>> -		/* We're not fetching the event so swap back again */
>> -		if (session->header.needs_swap)
>> -			perf_event_header__bswap(&event->header);
>> -		pr_debug("%s: head=%#" PRIx64 " event->header_size=%#x, mmap_size=%#zx: fuzzed perf.data?\n",
>> -			 __func__, head, event->header.size, mmap_size);
>> -		return ERR_PTR(-EINVAL);
>> -	}
>> +	pr_debug("%s: head=%#" PRIx64 " event->header_size=%#x, mmap_size=%#zx\n",
>> +		__func__, head, event->header.size, mmap_size);
> 
> you're missign the 'fuzzed perf.data?' in here
> 
> I think we should keep it just change to: 'fuzzed or compressed perf.data?'

Fixed in v3.

> 
> thanks,
> jirka

~Alexey