[PATCH v5 27/50] perf maps: Get map before returning in maps__find_by_name
From: Ian Rogers
Date: Mon Nov 27 2023 - 17:12:23 EST
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. Also fix some reference counted pointer comparisons.
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
tools/perf/tests/vmlinux-kallsyms.c | 5 +++--
tools/perf/util/machine.c | 6 ++++--
tools/perf/util/maps.c | 6 +++---
tools/perf/util/probe-event.c | 1 +
tools/perf/util/symbol-elf.c | 4 +++-
tools/perf/util/symbol.c | 20 ++++++++++++--------
6 files changed, 26 insertions(+), 16 deletions(-)
diff --git a/tools/perf/tests/vmlinux-kallsyms.c b/tools/perf/tests/vmlinux-kallsyms.c
index e808e6fc8f76..fecbf851bb2e 100644
--- a/tools/perf/tests/vmlinux-kallsyms.c
+++ b/tools/perf/tests/vmlinux-kallsyms.c
@@ -131,9 +131,10 @@ static int test__vmlinux_matches_kallsyms_cb1(struct map *map, void *data)
struct map *pair = maps__find_by_name(args->kallsyms.kmaps,
(dso->kernel ? dso->short_name : dso->name));
- if (pair)
+ if (pair) {
map__set_priv(pair, 1);
- else {
+ map__put(pair);
+ } else {
if (!args->header_printed) {
pr_info("WARN: Maps only in vmlinux:\n");
args->header_printed = true;
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 1112a9dbb21a..d6b3f84cb935 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1538,8 +1538,10 @@ static int maps__set_module_path(struct maps *maps, const char *path, struct kmo
return 0;
long_name = strdup(path);
- if (long_name == NULL)
+ if (long_name == NULL) {
+ map__put(map);
return -ENOMEM;
+ }
dso = map__dso(map);
dso__set_long_name(dso, long_name, true);
@@ -1553,7 +1555,7 @@ static int maps__set_module_path(struct maps *maps, const char *path, struct kmo
dso->symtab_type++;
dso->comp = m->comp;
}
-
+ map__put(map);
return 0;
}
diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
index 28facfdac1d7..8a8c1f216b86 100644
--- a/tools/perf/util/maps.c
+++ b/tools/perf/util/maps.c
@@ -885,7 +885,7 @@ struct map *maps__find_by_name(struct maps *maps, const char *name)
struct dso *dso = map__dso(maps__maps_by_name(maps)[i]);
if (dso && strcmp(dso->short_name, name) == 0) {
- result = maps__maps_by_name(maps)[i]; // TODO: map__get
+ result = map__get(maps__maps_by_name(maps)[i]);
done = true;
}
}
@@ -897,7 +897,7 @@ struct map *maps__find_by_name(struct maps *maps, const char *name)
sizeof(*mapp), map__strcmp_name);
if (mapp) {
- result = *mapp; // TODO: map__get
+ result = map__get(*mapp);
i = mapp - maps__maps_by_name(maps);
RC_CHK_ACCESS(maps)->last_search_by_name_idx = i;
}
@@ -922,7 +922,7 @@ struct map *maps__find_by_name(struct maps *maps, const char *name)
struct dso *dso = map__dso(pos);
if (dso && strcmp(dso->short_name, name) == 0) {
- result = pos; // TODO: map__get
+ result = map__get(pos);
break;
}
}
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index a1a796043691..be71abe8b9b0 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -358,6 +358,7 @@ static int kernel_get_module_dso(const char *module, struct dso **pdso)
map = maps__find_by_name(machine__kernel_maps(host_machine), module_name);
if (map) {
dso = map__dso(map);
+ map__put(map);
goto found;
}
pr_debug("Failed to find module %s.\n", module);
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 4b934ed3bfd1..5990e3fabdb5 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -1470,8 +1470,10 @@ static int dso__process_kernel_symbol(struct dso *dso, struct map *map,
dso__set_loaded(curr_dso);
*curr_mapp = curr_map;
*curr_dsop = curr_dso;
- } else
+ } else {
*curr_dsop = map__dso(curr_map);
+ map__put(curr_map);
+ }
return 0;
}
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index ad4819a24320..0785a54e832e 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -814,7 +814,7 @@ static int maps__split_kallsyms(struct maps *kmaps, struct dso *dso, u64 delta,
struct map *initial_map)
{
struct machine *machine;
- struct map *curr_map = initial_map;
+ struct map *curr_map = map__get(initial_map);
struct symbol *pos;
int count = 0, moved = 0;
struct rb_root_cached *root = &dso->symbols;
@@ -858,13 +858,14 @@ static int maps__split_kallsyms(struct maps *kmaps, struct dso *dso, u64 delta,
dso__set_loaded(curr_map_dso);
}
+ map__zput(curr_map);
curr_map = maps__find_by_name(kmaps, module);
if (curr_map == NULL) {
pr_debug("%s/proc/{kallsyms,modules} "
"inconsistency while looking "
"for \"%s\" module!\n",
machine->root_dir, module);
- curr_map = initial_map;
+ curr_map = map__get(initial_map);
goto discard_symbol;
}
curr_map_dso = map__dso(curr_map);
@@ -888,7 +889,7 @@ static int maps__split_kallsyms(struct maps *kmaps, struct dso *dso, u64 delta,
* symbols at this point.
*/
goto discard_symbol;
- } else if (curr_map != initial_map) {
+ } else if (!RC_CHK_EQUAL(curr_map, initial_map)) {
char dso_name[PATH_MAX];
struct dso *ndso;
@@ -899,7 +900,8 @@ static int maps__split_kallsyms(struct maps *kmaps, struct dso *dso, u64 delta,
}
if (count == 0) {
- curr_map = initial_map;
+ map__zput(curr_map);
+ curr_map = map__get(initial_map);
goto add_symbol;
}
@@ -913,6 +915,7 @@ static int maps__split_kallsyms(struct maps *kmaps, struct dso *dso, u64 delta,
kernel_range++);
ndso = dso__new(dso_name);
+ map__zput(curr_map);
if (ndso == NULL)
return -1;
@@ -926,6 +929,7 @@ static int maps__split_kallsyms(struct maps *kmaps, struct dso *dso, u64 delta,
map__set_mapping_type(curr_map, MAPPING_TYPE__IDENTITY);
if (maps__insert(kmaps, curr_map)) {
+ map__zput(curr_map);
dso__put(ndso);
return -1;
}
@@ -936,7 +940,7 @@ static int maps__split_kallsyms(struct maps *kmaps, struct dso *dso, u64 delta,
pos->end -= delta;
}
add_symbol:
- if (curr_map != initial_map) {
+ if (!RC_CHK_EQUAL(curr_map, initial_map)) {
struct dso *curr_map_dso = map__dso(curr_map);
rb_erase_cached(&pos->rb_node, root);
@@ -951,12 +955,12 @@ static int maps__split_kallsyms(struct maps *kmaps, struct dso *dso, u64 delta,
symbol__delete(pos);
}
- if (curr_map != initial_map &&
+ if (!RC_CHK_EQUAL(curr_map, initial_map) &&
dso->kernel == DSO_SPACE__KERNEL_GUEST &&
machine__is_default_guest(maps__machine(kmaps))) {
dso__set_loaded(map__dso(curr_map));
}
-
+ map__put(curr_map);
return count + moved;
}
@@ -1248,7 +1252,7 @@ static bool remove_old_maps(struct map *map, void *data)
* We need to preserve eBPF maps even if they are covered by kcore,
* because we need to access eBPF dso for source data.
*/
- return RC_CHK_ACCESS(map) != RC_CHK_ACCESS(map_to_save) && !__map__is_bpf_prog(map);
+ return !RC_CHK_EQUAL(map, map_to_save) && !__map__is_bpf_prog(map);
}
static int dso__load_kcore(struct dso *dso, struct map *map,
--
2.43.0.rc1.413.gea7ed67945-goog