[PATCH v3 04/22] perf dso: Hold lock when accessing nsinfo

[Ian Rogers <irogers@google.com>]

There may be threads racing to update dso->nsinfo:
https://lore.kernel.org/linux-perf-users/CAP-5=fWZH20L4kv-BwVtGLwR=Em3AOOT+Q4QGivvQuYn5AsPRg@mail.gmail.com/
Holding the dso->lock avoids use-after-free, memory leaks and other
such bugs. Apply the fix in:
https://lore.kernel.org/linux-perf-users/20211118193714.2293728-1-irogers@google.com/
of there being a missing nsinfo__put now that the accesses are data race
free.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-inject.c   | 4 ++++
 tools/perf/util/dso.c         | 5 ++++-
 tools/perf/util/map.c         | 3 +++
 tools/perf/util/probe-event.c | 2 ++
 tools/perf/util/symbol.c      | 2 +-
 5 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index fbf43a454cba..bede332bf0e2 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -363,8 +363,10 @@ static struct dso *findnew_dso(int pid, int tid, const char *filename,
 	}
 
 	if (dso) {
+		BUG_ON(pthread_mutex_lock(&dso->lock) != 0);
 		nsinfo__put(dso->nsinfo);
 		dso->nsinfo = nsi;
+		pthread_mutex_unlock(&dso->lock);
 	} else
 		nsinfo__put(nsi);
 
@@ -547,7 +549,9 @@ static int dso__read_build_id(struct dso *dso)
 	if (dso->has_build_id)
 		return 0;
 
+	BUG_ON(pthread_mutex_lock(&dso->lock) != 0);
 	nsinfo__mountns_enter(dso->nsinfo, &nsc);
+	pthread_mutex_unlock(&dso->lock);
 	if (filename__read_build_id(dso->long_name, &dso->bid) > 0)
 		dso->has_build_id = true;
 	nsinfo__mountns_exit(&nsc);
diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 6beccffeef7b..b2f570adba35 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -548,8 +548,11 @@ static int open_dso(struct dso *dso, struct machine *machine)
 	int fd;
 	struct nscookie nsc;
 
-	if (dso->binary_type != DSO_BINARY_TYPE__BUILD_ID_CACHE)
+	if (dso->binary_type != DSO_BINARY_TYPE__BUILD_ID_CACHE) {
+		BUG_ON(pthread_mutex_lock(&dso->lock) != 0);
 		nsinfo__mountns_enter(dso->nsinfo, &nsc);
+		pthread_mutex_unlock(&dso->lock);
+	}
 	fd = __open_dso(dso, machine);
 	if (dso->binary_type != DSO_BINARY_TYPE__BUILD_ID_CACHE)
 		nsinfo__mountns_exit(&nsc);
diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 8af693d9678c..ae99b52502d5 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -192,7 +192,10 @@ struct map *map__new(struct machine *machine, u64 start, u64 len,
 			if (!(prot & PROT_EXEC))
 				dso__set_loaded(dso);
 		}
+		BUG_ON(pthread_mutex_lock(&dso->lock) != 0);
+		nsinfo__put(dso->nsinfo);
 		dso->nsinfo = nsi;
+		pthread_mutex_unlock(&dso->lock);
 
 		if (build_id__is_defined(bid))
 			dso__set_build_id(dso, bid);
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index a834918a0a0d..7444e689ece7 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -180,8 +180,10 @@ struct map *get_target_map(const char *target, struct nsinfo *nsi, bool user)
 
 		map = dso__new_map(target);
 		if (map && map->dso) {
+			BUG_ON(pthread_mutex_lock(&map->dso->lock) != 0);
 			nsinfo__put(map->dso->nsinfo);
 			map->dso->nsinfo = nsinfo__get(nsi);
+			pthread_mutex_unlock(&map->dso->lock);
 		}
 		return map;
 	} else {
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 43f47532696f..a504346feb05 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1774,6 +1774,7 @@ int dso__load(struct dso *dso, struct map *map)
 	char newmapname[PATH_MAX];
 	const char *map_path = dso->long_name;
 
+	BUG_ON(pthread_mutex_lock(&dso->lock) != 0);
 	perfmap = strncmp(dso->name, "/tmp/perf-", 10) == 0;
 	if (perfmap) {
 		if (dso->nsinfo && (dso__find_perf_map(newmapname,
@@ -1783,7 +1784,6 @@ int dso__load(struct dso *dso, struct map *map)
 	}
 
 	nsinfo__mountns_enter(dso->nsinfo, &nsc);
-	BUG_ON(pthread_mutex_lock(&dso->lock) != 0);
 
 	/* check again under the dso->lock */
 	if (dso__loaded(dso)) {
-- 
2.35.1.265.g69c8d7142f-goog