linux-kernel - Re: [PATCH 09/15] perf tools: validate perf event header size

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Date:	Thu, 27 Jun 2013 10:59:41 +0300
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Jiri Olsa <jolsa@...hat.com>
CC:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	linux-kernel@...r.kernel.org, David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Mike Galbraith <efault@....de>,
	Namhyung Kim <namhyung@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 09/15] perf tools: validate perf event header size

On 25/06/13 16:18, Jiri Olsa wrote:
> On Mon, Jun 24, 2013 at 04:16:06PM +0300, Adrian Hunter wrote:
>> 'size' includes the header so must be at least
>> 'sizeof(struct perf_event_header)'.  Error out
>> immediately if that is not the case.  Also
>> don't byte-swap the header until it is actually
>> "fetched" from the mmap region.
>>
>> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
>> ---
>>  tools/perf/util/session.c | 14 ++++++++------
>>  1 file changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
>> index 19ea888..7e0d605 100644
>> --- a/tools/perf/util/session.c
>> +++ b/tools/perf/util/session.c
>> @@ -1094,8 +1094,10 @@ more:
>>  		perf_event_header__bswap(&event->header);
>>  
>>  	size = event->header.size;
>> -	if (size == 0)
>> -		size = 8;
>> +	if (size < sizeof(struct perf_event_header)) {
>> +		pr_err("bad event header size\n");
>> +		goto out_err;
>> +	}
>>  
>>  	if (size > cur_size) {
>>  		void *new = realloc(buf, size);
>> @@ -1161,12 +1163,12 @@ fetch_mmaped_event(struct perf_session *session,
>>  
>>  	event = (union perf_event *)(buf + head);
>>  
>> -	if (session->header.needs_swap)
>> -		perf_event_header__bswap(&event->header);
>> -
>>  	if (head + event->header.size > mmap_size)
>>  		return NULL;
> 
> dont we need to swap first before using event->header.size?

Thanks for reviewing.  Fixed in V2.

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