Re: [PATCH] perf data convert json: Fix trace_seq memory leak in process_sample_event()

[Tanushree Shah <tshah@linux.ibm.com>]

Hello Arnaldo

Thanks for checking the patch. I cannot see this patch applied on 
perf-tools-next yet.

https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/log/?h=perf-tools-next

Thanks.

On 05/06/26 02:59, Arnaldo Carvalho de Melo wrote:
> On Thu, Jun 04, 2026 at 12:25:19PM +0530, Tanushree Shah wrote:
>> Unlike the in-kernel trace_seq which uses a statically allocated buffer,
>> the userspace traceevent library's trace_seq uses a dynamically allocated
>> one. Therefore, every trace_seq_init() call must be paired with a
>> trace_seq_destroy(), otherwise it produces a memory leak.
>>
>> In process_sample_event(), a trace_seq is initialized for each field when
>> formatting tracepoint raw_data, but the matching trace_seq_destroy() is
>> never called, leaking memory for every field of every sample processed.
>>
>> Add the missing trace_seq_destroy() after using the trace_seq buffer to
>> properly free the allocated memory.
>>
>> Detected with Valgrind on a perf.data file with 2,729 tracepoint samples:
>>    Before: definitely lost: 55,537,664 bytes in 13,559 blocks
>>    After:  definitely lost: 0 bytes in 0 blocks
> 
> Thanks, applied to perf-tools-next, for v7.2.
> 
> - Arnaldo
>   
>> Fixes: 9d895e468429 ("perf data: Add tracepoint fields when converting to JSON")
>> Signed-off-by: Tanushree Shah <tshah@linux.ibm.com>
>> ---
>>   tools/perf/util/data-convert-json.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/tools/perf/util/data-convert-json.c b/tools/perf/util/data-convert-json.c
>> index d526c91312ed..6dd9349ab10f 100644
>> --- a/tools/perf/util/data-convert-json.c
>> +++ b/tools/perf/util/data-convert-json.c
>> @@ -257,6 +257,7 @@ static int process_sample_event(const struct perf_tool *tool,
>>   				trace_seq_init(&s);
>>   				tep_print_field(&s, sample->raw_data, fields[i]);
>>   				output_json_key_string(out, true, 3, fields[i]->name, s.buffer);
>> +				trace_seq_destroy(&s);
>>   
>>   				i++;
>>   			}
>> -- 
>> 2.47.3