Re: [PATCH v2 4/4] perf hists browser: Increase MAX_OPTIONS to prevent stack buffer overflow

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Uninitialized stack memory passed to free() on pstack__new() error path, causing heap corruption.
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--- Patch [4]: [PATCH v2 4/4] perf hists browser: Increase MAX_OPTIONS to prevent stack buffer overflow ---
commit a3310ba19dbf043afaf000421ada085b9b1e380f
Author: Ian Rogers <irogers@google.com>

perf hists browser: Increase MAX_OPTIONS to prevent stack buffer overflow

In evsel__hists_browse(), the 'options' and 'actions' arrays are statically
allocated on the stack with a size of MAX_OPTIONS (16). Depending on the
context, the sum of added options can theoretically exceed 16 (potentially
reaching up to ~19). This could lead to a stack buffer overflow, so this
patch increases MAX_OPTIONS to 32 to accommodate the maximum possible number
of options without risking an overflow.

Closes: https://lore.kernel.org/linux-perf-users/20260708235834.3FB771F00A3A@smtp.kernel.org/

> diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
> index a93846b8dc885..2b81217b02dfd 100644
> --- a/tools/perf/ui/browsers/hists.c
> +++ b/tools/perf/ui/browsers/hists.c
> @@ -3002,7 +3002,7 @@ static int evsel__hists_browse(struct evsel *evsel, int nr_events, const char *h
>  	struct hists *hists = evsel__hists(evsel);
>  	struct hist_browser *browser = perf_evsel_browser__new(evsel, hbt, env);
>  	struct branch_info *bi = NULL;
> -#define MAX_OPTIONS  16
> +#define MAX_OPTIONS  32
>  	char *options[MAX_OPTIONS];

[Severity: High]
This isn't a bug introduced by this patch, but if pstack__new() fails before
the array is initialized:

tools/perf/ui/browsers/hists.c:evsel__hists_browse() {
    ...
	browser->pstack = pstack__new(3);
	if (browser->pstack == NULL)
		goto out;

	ui_helpline__push(helpline);

	memset(options, 0, sizeof(options));
    ...
out:
	hist_browser__delete(browser);
	free_popup_options(options, MAX_OPTIONS);
    ...
}

Does this pass uninitialized stack memory to free_popup_options(), which could
cause heap corruption when it attempts to free garbage stack pointers?

>  	struct popup_action actions[MAX_OPTIONS];
>  	int nr_options = 0;

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Sashiko AI review · https://sashiko.dev/#/patchset/20260709033701.1117943-1-irogers@google.com?part=4