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

[Arnaldo Carvalho de Melo <acme@kernel.org>]

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