Received-SPF: pass (google.com: domain of linux-kernel+bounces-57263-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Date: Wed,  7 Feb 2024 14:36:37 -0800
In-Reply-To: <20240207223639.3139601-1-irogers@google.com>
Message-Id: <20240207223639.3139601-5-irogers@google.com>
Precedence: bulk
Mime-Version: 1.0
References: <20240207223639.3139601-1-irogers@google.com>
Subject: [PATCH v2 4/6] perf maps: Get map before returning in maps__find_next_entry
From: Ian Rogers <irogers@google.com>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, 
	Arnaldo Carvalho de Melo <acme@kernel.org>, Namhyung Kim <namhyung@kernel.org>, 
	Mark Rutland <mark.rutland@arm.com>, 
	Alexander Shishkin <alexander.shishkin@linux.intel.com>, Jiri Olsa <jolsa@kernel.org>, 
	Ian Rogers <irogers@google.com>, Adrian Hunter <adrian.hunter@intel.com>, Song Liu <song@kernel.org>, 
	Miguel Ojeda <ojeda@kernel.org>, Liam Howlett <liam.howlett@oracle.com>, 
	Colin Ian King <colin.i.king@gmail.com>, K Prateek Nayak <kprateek.nayak@amd.com>, 
	Artem Savkov <asavkov@redhat.com>, Changbin Du <changbin.du@huawei.com>, 
	Masami Hiramatsu <mhiramat@kernel.org>, Athira Rajeev <atrajeev@linux.vnet.ibm.com>, 
	Yang Jihong <yangjihong1@huawei.com>, Tiezhu Yang <yangtiezhu@loongson.cn>, 
	James Clark <james.clark@arm.com>, Leo Yan <leo.yan@linaro.org>, 
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, 
	bpf@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"

Finding a map is done under a lock, returning the map without a
reference count means it can be removed without notice and causing
uses after free. Grab a reference count to the map within the lock
region and return this. Fix up locations that need a map__put
following this.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/util/machine.c | 4 +++-
 tools/perf/util/maps.c    | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 7031f6fddcae..4911734411b5 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1761,8 +1761,10 @@ int machine__create_kernel_maps(struct machine *machine)
 		struct map *next = maps__find_next_entry(machine__kernel_maps(machine),
 							 machine__kernel_map(machine));
 
-		if (next)
+		if (next) {
 			machine__set_kernel_mmap(machine, start, map__start(next));
+			map__put(next);
+		}
 	}
 
 out_put:
diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
index f4855e2bfd6e..e577909456be 100644
--- a/tools/perf/util/maps.c
+++ b/tools/perf/util/maps.c
@@ -956,7 +956,7 @@ struct map *maps__find_next_entry(struct maps *maps, struct map *map)
 	down_read(maps__lock(maps));
 	i = maps__by_address_index(maps, map);
 	if (i < maps__nr_maps(maps))
-		result = maps__maps_by_address(maps)[i]; // TODO: map__get
+		result = map__get(maps__maps_by_address(maps)[i]);
 
 	up_read(maps__lock(maps));
 	return result;
-- 
2.43.0.594.gd9cf4e227d-goog