[PATCH v4 6/9] perf ui hists: Fix dso_filter reference leak and exit cleanup

[Ian Rogers <irogers@google.com>]

In hists_browser__zoom_map(), the active dso is assigned as a raw
pointer to hists->dso_filter without acquiring a reference using
dso__get(). This creates a potential use-after-free defect if the
underlying dso is released while the filter remains active.

Fix it by properly acquiring a reference via dso__get() when assigning
the filter, and releasing it with dso__put() when clearing it.
Additionally, ensure that both hists->thread_filter and
hists->dso_filter are safely cleared and dropped upon exiting the
browser in evsel__hists_browse() to prevent leaking active references.

Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/linux-perf-users/20260709170834.52F1A1F000E9@smtp.kernel.org/
Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/ui/browsers/hists.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 70f8a820d0a0..316db603bf25 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -2640,13 +2640,14 @@ static int hists_browser__zoom_map(struct hist_browser *browser, struct map *map
 	if (browser->hists->dso_filter) {
 		pstack__remove(browser->pstack, &browser->hists->dso_filter);
 		perf_hpp__set_elide(HISTC_DSO, false);
+		dso__put((struct dso *)browser->hists->dso_filter);
 		browser->hists->dso_filter = NULL;
 		ui_helpline__pop();
 	} else {
 		struct dso *dso = map__dso(map);
 		ui_helpline__fpush("To zoom out press ESC or ENTER + \"Zoom out of %s DSO\"",
 				   __map__is_kernel(map) ? "the Kernel" : dso__short_name(dso));
-		browser->hists->dso_filter = dso;
+		browser->hists->dso_filter = dso__get(dso);
 		perf_hpp__set_elide(HISTC_DSO, true);
 		pstack__push(browser->pstack, &browser->hists->dso_filter);
 	}
@@ -3450,6 +3451,9 @@ static int evsel__hists_browse(struct evsel *evsel, int nr_events, const char *h
 	}
 out_free_stack:
 	pstack__delete(browser->pstack);
+	thread__zput(hists->thread_filter);
+	dso__put((struct dso *)hists->dso_filter);
+	hists->dso_filter = NULL;
 out:
 	hist_browser__delete(browser);
 	free_popup_options(options, MAX_OPTIONS);
-- 
2.55.0.795.g602f6c329a-goog