From 8f77b455f768d1f95971cedd8d4903f249f683bf 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.

Resolves: #1667871

---

 src/libsystemd/sd-bus/bus-objects.c | 58 +++++++++++++++++++++++------

 1 file changed, 46 insertions(+), 12 deletions(-)

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

index fc6c223283..8df73bdf4c 100644

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

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

@@ -1104,7 +1104,8 @@ 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);

@@ -1120,7 +1121,12 @@ 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)

@@ -1316,6 +1322,7 @@ 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;

@@ -1340,9 +1347,12 @@ 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);

@@ -2044,9 +2054,10 @@ _public_ int sd_bus_emit_properties_changed_strv(

                 const char *interface,

                 char **names) {

+        _cleanup_free_ char *prefix = NULL;

         BUS_DONT_DESTROY(bus);

         bool found_interface = false;

-        char *prefix;

+        size_t pl;

         int r;

         assert_return(bus, -EINVAL);

@@ -2064,6 +2075,12 @@ _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;

@@ -2073,7 +2090,6 @@ _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)

@@ -2204,7 +2220,8 @@ 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);

@@ -2249,7 +2266,12 @@ 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)

@@ -2380,7 +2402,8 @@ 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);

@@ -2412,7 +2435,12 @@ 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)

@@ -2554,7 +2582,8 @@ 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);

@@ -2568,7 +2597,12 @@ 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)