perf maps: Get map before returning in maps__find

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>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: James Clark <james.clark@arm.com>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Leo Yan <leo.yan@linux.dev>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Artem Savkov <asavkov@redhat.com>
Cc: bpf@vger.kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240210031746.4057262-3-irogers@google.com

1 files changed, 8 insertions, 14 deletions

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index b397a769006f..e8eb9f0b073f 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -896,7 +896,6 @@ static int machine__process_ksymbol_register(struct machine *machine,
 	struct symbol *sym;
 	struct dso *dso;
 	struct map *map = maps__find(machine__kernel_maps(machine), event->ksymbol.addr);
-	bool put_map = false;
 	int err = 0;
 
 	if (!map) {
@@ -913,12 +912,6 @@ static int machine__process_ksymbol_register(struct machine *machine,
 			err = -ENOMEM;
 			goto out;
 		}
-		/*
-		 * The inserted map has a get on it, we need to put to release
-		 * the reference count here, but do it after all accesses are
-		 * done.
-		 */
-		put_map = true;
 		if (event->ksymbol.ksym_type == PERF_RECORD_KSYMBOL_TYPE_OOL) {
 			dso->binary_type = DSO_BINARY_TYPE__OOL;
 			dso->data.file_size = event->ksymbol.len;
@@ -952,8 +945,7 @@ static int machine__process_ksymbol_register(struct machine *machine,
 	}
 	dso__insert_symbol(dso, sym);
 out:
-	if (put_map)
-		map__put(map);
+	map__put(map);
 	return err;
 }
 
@@ -977,7 +969,7 @@ static int machine__process_ksymbol_unregister(struct machine *machine,
 		if (sym)
 			dso__delete_symbol(dso, sym);
 	}
-
+	map__put(map);
 	return 0;
 }
 
@@ -1005,11 +997,11 @@ int machine__process_text_poke(struct machine *machine, union perf_event *event,
 		perf_event__fprintf_text_poke(event, machine, stdout);
 
 	if (!event->text_poke.new_len)
-		return 0;
+		goto out;
 
 	if (cpumode != PERF_RECORD_MISC_KERNEL) {
 		pr_debug("%s: unsupported cpumode - ignoring\n", __func__);
-		return 0;
+		goto out;
 	}
 
 	if (dso) {
@@ -1032,7 +1024,8 @@ int machine__process_text_poke(struct machine *machine, union perf_event *event,
 		pr_debug("Failed to find kernel text poke address map for %#" PRI_lx64 "\n",
 			 event->text_poke.addr);
 	}
-
+out:
+	map__put(map);
 	return 0;
 }
 
@@ -1300,9 +1293,10 @@ static int machine__map_x86_64_entry_trampolines_cb(struct map *map, void *data)
 		return 0;
 
 	dest_map = maps__find(args->kmaps, map__pgoff(map));
-	if (dest_map != map)
+	if (RC_CHK_ACCESS(dest_map) != RC_CHK_ACCESS(map))
 		map__set_pgoff(map, map__map_ip(dest_map, map__pgoff(map)));
 
+	map__put(dest_map);
 	args->found = true;
 	return 0;
 }