From 5eb96e51ca2ce0e90e90ecb9f78e8305f51fa5dd Mon Sep 17 00:00:00 2001

From: Riccardo Schirone <rschiron@redhat.com>

Date: Mon, 4 Feb 2019 14:29:28 +0100

Subject: [PATCH] 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 f519a19bcd5afe674a9b8fc462cd77d8bad403c1)

Related: #1678641

---

 src/libsystemd/sd-bus/bus-objects.c | 68 +++++++++++++++++++++++------

 1 file changed, 54 insertions(+), 14 deletions(-)

diff --git a/src/libsystemd/sd-bus/bus-objects.c b/src/libsystemd/sd-bus/bus-objects.c

index a18ff88b07..53bf0fd620 100644

--- a/src/libsystemd/sd-bus/bus-objects.c

+++ b/src/libsystemd/sd-bus/bus-objects.c

@@ -1134,7 +1134,8 @@ 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);

@@ -1150,7 +1151,12 @@ 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)

@@ -1346,6 +1352,7 @@ 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;

@@ -1370,9 +1377,12 @@ 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);

@@ -1499,9 +1509,15 @@ 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)

@@ -2090,8 +2106,9 @@ _public_ int sd_bus_emit_properties_changed_strv(

                 const char *interface,

                 char **names) {

+        _cleanup_free_ char *prefix = NULL;

         bool found_interface = false;

-        char *prefix;

+        size_t pl;

         int r;

         assert_return(bus, -EINVAL);

@@ -2112,6 +2129,12 @@ _public_ int sd_bus_emit_properties_changed_strv(

         BUS_DONT_DESTROY(bus);

+        pl = strlen(path);

+        assert(pl <= BUS_PATH_SIZE_MAX);

+        prefix = new(char, pl + 1);

+        if (!prefix)

+                return -ENOMEM;

+

         do {

                 bus->nodes_modified = false;

@@ -2121,7 +2144,6 @@ _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)

@@ -2253,7 +2275,8 @@ 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);

@@ -2298,7 +2321,12 @@ 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)

@@ -2437,7 +2465,8 @@ 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);

@@ -2469,7 +2498,12 @@ 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)

@@ -2619,7 +2653,8 @@ 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);

@@ -2633,7 +2668,12 @@ 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)