Re: [PATCH 11/12] perf jitdump: Validate sym string NUL-termination in code load

[Ian Rogers]

On Wed, Aug 5, 2026 at 6:32 AM Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
>
> From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
>
> jit_repipe_code_load() computes sym = (void *)jr + sizeof(jr->load) and
> passes it to jit_emit_elf() which calls strlen(sym) via jit_write_elf().
> If code_size equals total_size - sizeof(jr->load), the sym pointer
> aliases the code blob with no NUL terminator, and strlen() scans past
> the buffer into adjacent heap memory.
>
> Add a memchr() check to verify the symbol name is NUL-terminated within
> the region between the load header and the code blob before use.
>
> Fixes: 598b7c6919c7bbcc ("perf jit: add source line info support")
> Reported-by: sashiko-bot <sashiko-bot@xxxxxxxxxx>
> Cc: Stephane Eranian <eranian@xxxxxxxxxx>
> Assisted-by: Claude:claude-opus-4.6
> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks!
Ian

> ---
>  tools/perf/util/jitdump.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/tools/perf/util/jitdump.c b/tools/perf/util/jitdump.c
> index 87612ef3e232598e..5f3a53f818c29f58 100644
> --- a/tools/perf/util/jitdump.c
> +++ b/tools/perf/util/jitdump.c
> @@ -487,6 +487,13 @@ static int jit_repipe_code_load(struct jit_buf_desc *jd, union jr_entry *jr)
>
>         sym   = (void *)((unsigned long)jr + sizeof(jr->load));
>         code  = (unsigned long)jr + jr->load.p.total_size - csize;
> +
> +       /* sym string lives between the load header and the code blob */
> +       if (!memchr(sym, '\0', code - (unsigned long)sym)) {
> +               pr_warning("jitdump: unterminated symbol name in code_load record\n");
> +               return -1;
> +       }
> +
>         count = jr->load.code_index;
>         idr_size = jd->machine->id_hdr_size;
>
> --
> 2.55.0
>