Re: [PATCH v2] perf disasm: Fix potential use-after-free on fileloc

Namhyung Kim
2026-03-12T01:18:00Z

On Fri, Mar 06, 2026 at 04:22:22PM -0800, Ian Rogers wrote:
> The fileloc is a copy of a pointer to a string but in places like
> symbol_disassemble__llvm this string appears to be freed setting up
> potential use-after-frees:
>
> llvm.c:
> ```
> dl = disasm_line__new(args);
> if (dl == NULL)
> goto err;
>
> annotation_line__add(&dl->al, &notes->src->source);
>
> free(args->fileloc);
> ```
> disasm.c:
> ```
> static void annotation_line__init(struct annotation_line *al,
> struct annotate_args *args,
> int nr)
> {
> al->offset = args->offset;
> al->line = strdup(args->line);
> al->line_nr = args->line_nr;
> al->fileloc = args->fileloc;
> al->data_nr = nr;
> }
>
> struct disasm_line *disasm_line__new(struct annotate_args *args)
> {
> struct disasm_line *dl = NULL;
> struct annotation *notes = symbol__annotation(args->ms->sym);
> int nr = notes->src->nr_events;
>
> dl = zalloc(disasm_line_size(nr));
> if (!dl)
> return NULL;
>
> annotation_line__init(&dl->al, args, nr);
> ```
>
> Fix this by making the fileloc a copy of the underlying string in its
> init/exit.
>
> Signed-off-by: Ian Rogers <irogers@google.com>

Applied to perf-tools-next, thanks!

Best regards,
Namhyung