[PATCH v1 1/3] perf maps: Fix use after free in __maps__fixup_overlap_and_insert

[Ian Rogers]

In the case 'before' and 'after' are broken out from pos,
maps_by_address may be changed by __maps__insert, as such it needs
re-reading.

Don't ignore the return value from __maps_insert.

Fixes: 659ad3492b91 ("perf maps: Switch from rbtree to lazily sorted array for addresses")
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
 tools/perf/util/maps.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
index 16b39db594f4..eaada3e0f5b4 100644
--- a/tools/perf/util/maps.c
+++ b/tools/perf/util/maps.c
@@ -741,7 +741,6 @@ static unsigned int first_ending_after(struct maps *maps, const struct map *map)
  */
 static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
 {
-	struct map **maps_by_address;
 	int err = 0;
 	FILE *fp = debug_file();
 
@@ -749,12 +748,12 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
 	if (!maps__maps_by_address_sorted(maps))
 		__maps__sort_by_address(maps);
 
-	maps_by_address = maps__maps_by_address(maps);
 	/*
 	 * Iterate through entries where the end of the existing entry is
 	 * greater-than the new map's start.
 	 */
 	for (unsigned int i = first_ending_after(maps, new); i < maps__nr_maps(maps); ) {
+		struct map **maps_by_address = maps__maps_by_address(maps);
 		struct map *pos = maps_by_address[i];
 		struct map *before = NULL, *after = NULL;
 
@@ -821,8 +820,10 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
 			/* Maps are still ordered, go to next one. */
 			i++;
 			if (after) {
-				__maps__insert(maps, after);
+				err = __maps__insert(maps, after);
 				map__put(after);
+				if (err)
+					goto out_err;
 				if (!maps__maps_by_address_sorted(maps)) {
 					/*
 					 * Sorting broken so invariants don't
@@ -851,7 +852,7 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
 		check_invariants(maps);
 	}
 	/* Add the map. */
-	__maps__insert(maps, new);
+	err = __maps__insert(maps, new);
 out_err:
 	return err;
 }
-- 
2.45.0.rc1.225.g2a3ae87e7f-goog