Description: sd-bus: enforce a size limit for dbus paths, and don't allocate them on the stacka Forwarded: no Patch from: systemd_239-7ubuntu10.8 For information see: https://usn.ubuntu.com/3891-1/ https://git.launchpad.net/ubuntu/+source/systemd/commit/?id=f8e75d5634904c8e672658856508c3a02f349adb CVE: CVE-2019-6454 Upstream-Status: Backport Signed-off-by: George McCollister diff --git a/src/libsystemd/sd-bus/bus-internal.c b/src/libsystemd/sd-bus/bus-internal.c index 40acae2133..598b7f110c 100644 --- a/src/libsystemd/sd-bus/bus-internal.c +++ b/src/libsystemd/sd-bus/bus-internal.c @@ -43,7 +43,7 @@ bool object_path_is_valid(const char *p) { if (slash) return false; - return true; + return (q - p) <= BUS_PATH_SIZE_MAX; } char* object_path_startswith(const char *a, const char *b) { diff --git a/src/libsystemd/sd-bus/bus-internal.h b/src/libsystemd/sd-bus/bus-internal.h index f208b294d8..a8d61bf72a 100644 --- a/src/libsystemd/sd-bus/bus-internal.h +++ b/src/libsystemd/sd-bus/bus-internal.h @@ -332,6 +332,10 @@ struct sd_bus { #define BUS_MESSAGE_SIZE_MAX (128*1024*1024) #define BUS_AUTH_SIZE_MAX (64*1024) +/* Note that the D-Bus specification states that bus paths shall have no size limit. We enforce here one + * anyway, since truly unbounded strings are a security problem. The limit we pick is relatively large however, + * to not clash unnecessarily with real-life applications. */ +#define BUS_PATH_SIZE_MAX (64*1024) #define BUS_CONTAINER_DEPTH 128 diff --git a/src/libsystemd/sd-bus/bus-objects.c b/src/libsystemd/sd-bus/bus-objects.c index 58329f3fe7..54b977418e 100644 --- a/src/libsystemd/sd-bus/bus-objects.c +++ b/src/libsystemd/sd-bus/bus-objects.c @@ -1133,7 +1133,8 @@ 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); @@ -1149,7 +1150,12 @@ static int object_manager_serialize_path_and_fallbacks( return 0; /* Second, add fallback vtables registered for any of the prefixes */ - prefix = newa(char, 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) @@ -1345,6 +1351,7 @@ 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; @@ -1369,9 +1376,12 @@ 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); @@ -1498,9 +1508,15 @@ 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 = newa(char, strlen(path) + 1); OBJECT_PATH_FOREACH_PREFIX(prefix, path) { n = hashmap_get(bus->nodes, prefix); if (n) @@ -2083,8 +2099,9 @@ _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); @@ -2105,6 +2122,12 @@ _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; @@ -2114,7 +2137,6 @@ _public_ int sd_bus_emit_properties_changed_strv( if (bus->nodes_modified) continue; - prefix = newa(char, 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) @@ -2246,7 +2268,8 @@ 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); @@ -2291,7 +2314,12 @@ static int object_added_append_all(sd_bus *bus, sd_bus_message *m, const char *p if (bus->nodes_modified) return 0; - prefix = newa(char, 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) @@ -2430,7 +2458,8 @@ 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); @@ -2462,7 +2491,12 @@ static int object_removed_append_all(sd_bus *bus, sd_bus_message *m, const char if (bus->nodes_modified) return 0; - prefix = newa(char, 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) @@ -2612,7 +2646,8 @@ 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); @@ -2626,7 +2661,12 @@ static int interfaces_added_append_one( if (bus->nodes_modified) return 0; - prefix = newa(char, 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)