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Allocate temporary strings to hold dbus paths on the heap

Paths are limited to BUS_PATH_SIZE_MAX but the maximum size is anyway too big
to be allocated on the stack, so let's switch to the heap where there is a
clear way to understand if the allocation fails.

(cherry picked from commit f519a19)
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Riccardo Schirone authored and keszybz committed Feb 4, 2019
1 parent c83cf4a commit 07f8cd571e22e892d68932fe9e7fcf92c7ca7d5c
Showing with 54 additions and 14 deletions.
  1. +54 −14 src/libsystemd/sd-bus/bus-objects.c
@@ -1150,7 +1150,8 @@ static int object_manager_serialize_path_and_fallbacks(
const char *path,
sd_bus_error *error) {

char *prefix;
_cleanup_free_ char *prefix = NULL;
size_t pl;
int r;

assert(bus);
@@ -1166,7 +1167,12 @@ static int object_manager_serialize_path_and_fallbacks(
return 0;

/* Second, add fallback vtables registered for any of the prefixes */
prefix = alloca(strlen(path) + 1);
pl = strlen(path);
assert(pl <= BUS_PATH_SIZE_MAX);
prefix = new(char, pl + 1);
if (!prefix)
return -ENOMEM;

OBJECT_PATH_FOREACH_PREFIX(prefix, path) {
r = object_manager_serialize_path(bus, reply, prefix, path, true, error);
if (r < 0)
@@ -1362,6 +1368,7 @@ static int object_find_and_run(
}

int bus_process_object(sd_bus *bus, sd_bus_message *m) {
_cleanup_free_ char *prefix = NULL;
int r;
size_t pl;
bool found_object = false;
@@ -1386,9 +1393,12 @@ int bus_process_object(sd_bus *bus, sd_bus_message *m) {
assert(m->member);

pl = strlen(m->path);
do {
char prefix[pl+1];
assert(pl <= BUS_PATH_SIZE_MAX);
prefix = new(char, pl + 1);
if (!prefix)
return -ENOMEM;

do {
bus->nodes_modified = false;

r = object_find_and_run(bus, m, m->path, false, &found_object);
@@ -1516,9 +1526,15 @@ static int bus_find_parent_object_manager(sd_bus *bus, struct node **out, const

n = hashmap_get(bus->nodes, path);
if (!n) {
char *prefix;
_cleanup_free_ char *prefix = NULL;
size_t pl;

pl = strlen(path);
assert(pl <= BUS_PATH_SIZE_MAX);
prefix = new(char, pl + 1);
if (!prefix)
return -ENOMEM;

prefix = alloca(strlen(path) + 1);
OBJECT_PATH_FOREACH_PREFIX(prefix, path) {
n = hashmap_get(bus->nodes, prefix);
if (n)
@@ -2108,8 +2124,9 @@ _public_ int sd_bus_emit_properties_changed_strv(
char **names) {

BUS_DONT_DESTROY(bus);
_cleanup_free_ char *prefix = NULL;
bool found_interface = false;
char *prefix;
size_t pl;
int r;

assert_return(bus, -EINVAL);
@@ -2128,6 +2145,12 @@ _public_ int sd_bus_emit_properties_changed_strv(
if (names && names[0] == NULL)
return 0;

pl = strlen(path);
assert(pl <= BUS_PATH_SIZE_MAX);
prefix = new(char, pl + 1);
if (!prefix)
return -ENOMEM;

do {
bus->nodes_modified = false;

@@ -2137,7 +2160,6 @@ _public_ int sd_bus_emit_properties_changed_strv(
if (bus->nodes_modified)
continue;

prefix = alloca(strlen(path) + 1);
OBJECT_PATH_FOREACH_PREFIX(prefix, path) {
r = emit_properties_changed_on_interface(bus, prefix, path, interface, true, &found_interface, names);
if (r != 0)
@@ -2269,7 +2291,8 @@ static int object_added_append_all_prefix(

static int object_added_append_all(sd_bus *bus, sd_bus_message *m, const char *path) {
_cleanup_set_free_ Set *s = NULL;
char *prefix;
_cleanup_free_ char *prefix = NULL;
size_t pl;
int r;

assert(bus);
@@ -2314,7 +2337,12 @@ static int object_added_append_all(sd_bus *bus, sd_bus_message *m, const char *p
if (bus->nodes_modified)
return 0;

prefix = alloca(strlen(path) + 1);
pl = strlen(path);
assert(pl <= BUS_PATH_SIZE_MAX);
prefix = new(char, pl + 1);
if (!prefix)
return -ENOMEM;

OBJECT_PATH_FOREACH_PREFIX(prefix, path) {
r = object_added_append_all_prefix(bus, m, s, prefix, path, true);
if (r < 0)
@@ -2453,7 +2481,8 @@ static int object_removed_append_all_prefix(

static int object_removed_append_all(sd_bus *bus, sd_bus_message *m, const char *path) {
_cleanup_set_free_ Set *s = NULL;
char *prefix;
_cleanup_free_ char *prefix = NULL;
size_t pl;
int r;

assert(bus);
@@ -2485,7 +2514,12 @@ static int object_removed_append_all(sd_bus *bus, sd_bus_message *m, const char
if (bus->nodes_modified)
return 0;

prefix = alloca(strlen(path) + 1);
pl = strlen(path);
assert(pl <= BUS_PATH_SIZE_MAX);
prefix = new(char, pl + 1);
if (!prefix)
return -ENOMEM;

OBJECT_PATH_FOREACH_PREFIX(prefix, path) {
r = object_removed_append_all_prefix(bus, m, s, prefix, path, true);
if (r < 0)
@@ -2635,7 +2669,8 @@ static int interfaces_added_append_one(
const char *path,
const char *interface) {

char *prefix;
_cleanup_free_ char *prefix = NULL;
size_t pl;
int r;

assert(bus);
@@ -2649,7 +2684,12 @@ static int interfaces_added_append_one(
if (bus->nodes_modified)
return 0;

prefix = alloca(strlen(path) + 1);
pl = strlen(path);
assert(pl <= BUS_PATH_SIZE_MAX);
prefix = new(char, pl + 1);
if (!prefix)
return -ENOMEM;

OBJECT_PATH_FOREACH_PREFIX(prefix, path) {
r = interfaces_added_append_one_prefix(bus, m, prefix, path, interface, true);
if (r != 0)

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