Re: [PATCH 3/5] perf jitdump: Free unwinding data even when eh_frame_hdr_size is zero

[Ian Rogers]

On Thu, Sep 3, 2026 at 6:23 AM Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
>
> From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
>
> jit_repipe_code_load() only cleared the unwinding state when both
> unwinding_data and eh_frame_hdr_size were set.  When a record carries
> unwinding data but eh_frame_hdr_size is 0, the cleanup condition fails
> and the unwinding state persists in jd, being applied to all subsequent
> JIT_CODE_LOAD and JIT_CODE_MOVE records, duplicating unwinding sections
> in the generated ELF files and inflating their event->mmap2.len.
>
> The record is validated upstream so eh_frame_hdr_size <= unwinding_size
> always holds.  Free the unwinding data based on the data pointer alone.
>
> Reported-by: sashiko-bot <sashiko-bot@xxxxxxxxxx>
> Cc: Stephane Eranian <eranian@xxxxxxxxxx>
> Assisted-by: LLM
> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  tools/perf/util/jitdump.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/jitdump.c b/tools/perf/util/jitdump.c
> index e0d5cc9a828189a2..efb40d93e33ae664 100644
> --- a/tools/perf/util/jitdump.c
> +++ b/tools/perf/util/jitdump.c
> @@ -530,7 +530,7 @@ static int jit_repipe_code_load(struct jit_buf_desc *jd, union jr_entry *jr)
>                 jd->nr_debug_entries = 0;
>         }
>
> -       if (jd->unwinding_data && jd->eh_frame_hdr_size) {
> +       if (jd->unwinding_data) {
>                 zfree(&jd->unwinding_data);
>                 jd->eh_frame_hdr_size = 0;
>                 jd->unwinding_mapped_size = 0;
> --
> 2.55.0
>