[OE-core] [PATCH] systemd: fix CVE-2019-6454
George McCollister
george.mccollister at gmail.com
Fri Feb 22 16:54:50 UTC 2019
Apply patches from systemd_239-7ubuntu10.8 to fix CVE-2019-6454.
CVE-2019-6454 is an issue in which systemd (PID1) can be crashed with a
specially formed D-Bus message.
For information see:
https://usn.ubuntu.com/3891-1/
https://git.launchpad.net/ubuntu/+source/systemd/commit/?id=f8e75d5634904c8e672658856508c3a02f349adb
Signed-off-by: George McCollister <george.mccollister at gmail.com>
---
.../systemd/systemd/CVE-2019-6454.patch | 210 ++++++++++++++++++
...eive-an-invalid-dbus-message-ignore-.patch | 61 +++++
meta/recipes-core/systemd/systemd_239.bb | 2 +
3 files changed, 273 insertions(+)
create mode 100644 meta/recipes-core/systemd/systemd/CVE-2019-6454.patch
create mode 100644 meta/recipes-core/systemd/systemd/sd-bus-if-we-receive-an-invalid-dbus-message-ignore-.patch
diff --git a/meta/recipes-core/systemd/systemd/CVE-2019-6454.patch b/meta/recipes-core/systemd/systemd/CVE-2019-6454.patch
new file mode 100644
index 0000000000..80170dac0f
--- /dev/null
+++ b/meta/recipes-core/systemd/systemd/CVE-2019-6454.patch
@@ -0,0 +1,210 @@
+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 <george.mccollister at gmail.com>
+
+--- a/src/libsystemd/sd-bus/bus-internal.c
++++ b/src/libsystemd/sd-bus/bus-internal.c
+@@ -45,7 +45,7 @@
+ if (slash)
+ return false;
+
+- return true;
++ return (q - p) <= BUS_PATH_SIZE_MAX;
+ }
+
+ char* object_path_startswith(const char *a, const char *b) {
+--- a/src/libsystemd/sd-bus/bus-internal.h
++++ b/src/libsystemd/sd-bus/bus-internal.h
+@@ -333,6 +333,10 @@
+
+ #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
+
+--- a/src/libsystemd/sd-bus/bus-objects.c
++++ b/src/libsystemd/sd-bus/bus-objects.c
+@@ -1134,7 +1134,8 @@
+ 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 @@
+ 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 @@
+ }
+
+ 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 @@
+ 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 @@
+
+ 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)
+@@ -2091,8 +2107,9 @@
+ 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);
+@@ -2111,6 +2128,12 @@
+ 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;
+
+@@ -2120,7 +2143,6 @@
+ 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)
+@@ -2252,7 +2274,8 @@
+
+ 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);
+@@ -2297,7 +2320,12 @@
+ 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)
+@@ -2436,7 +2464,8 @@
+
+ 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);
+@@ -2468,7 +2497,12 @@
+ 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)
+@@ -2618,7 +2652,8 @@
+ const char *path,
+ const char *interface) {
+
+- char *prefix;
++ _cleanup_free_ char *prefix = NULL;
++ size_t pl;
+ int r;
+
+ assert(bus);
+@@ -2632,7 +2667,12 @@
+ 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)
diff --git a/meta/recipes-core/systemd/systemd/sd-bus-if-we-receive-an-invalid-dbus-message-ignore-.patch b/meta/recipes-core/systemd/systemd/sd-bus-if-we-receive-an-invalid-dbus-message-ignore-.patch
new file mode 100644
index 0000000000..57311faa60
--- /dev/null
+++ b/meta/recipes-core/systemd/systemd/sd-bus-if-we-receive-an-invalid-dbus-message-ignore-.patch
@@ -0,0 +1,61 @@
+Description: sd-bus: if we receive an invalid dbus message, ignore and
+ proceeed
+ .
+ dbus-daemon might have a slightly different idea of what a valid msg is
+ than us (for example regarding valid msg and field sizes). Let's hence
+ try to proceed if we can and thus drop messages rather than fail the
+ connection if we fail to validate a message.
+ .
+ Hopefully the differences in what is considered valid are not visible
+ for real-life usecases, but are specific to exploit attempts only.
+Author: Lennart Poettering <lennart at poettering.net>
+Forwarded: other,https://github.com/systemd/systemd/pull/11708/
+
+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 <george.mccollister at gmail.com>
+
+diff --git a/src/libsystemd/sd-bus/bus-socket.c b/src/libsystemd/sd-bus/bus-socket.c
+index 30d6455b6f..441b4a816f 100644
+--- a/src/libsystemd/sd-bus/bus-socket.c
++++ b/src/libsystemd/sd-bus/bus-socket.c
+@@ -1072,7 +1072,7 @@ static int bus_socket_read_message_need(sd_bus *bus, size_t *need) {
+ }
+
+ static int bus_socket_make_message(sd_bus *bus, size_t size) {
+- sd_bus_message *t;
++ sd_bus_message *t = NULL;
+ void *b;
+ int r;
+
+@@ -1097,7 +1097,9 @@ static int bus_socket_make_message(sd_bus *bus, size_t size) {
+ bus->fds, bus->n_fds,
+ NULL,
+ &t);
+- if (r < 0) {
++ if (r == -EBADMSG)
++ log_debug_errno(r, "Received invalid message from connection %s, dropping.", strna(bus->description));
++ else if (r < 0) {
+ free(b);
+ return r;
+ }
+@@ -1108,7 +1110,8 @@ static int bus_socket_make_message(sd_bus *bus, size_t size) {
+ bus->fds = NULL;
+ bus->n_fds = 0;
+
+- bus->rqueue[bus->rqueue_size++] = t;
++ if (t)
++ bus->rqueue[bus->rqueue_size++] = t;
+
+ return 1;
+ }
+--
+2.17.1
+
diff --git a/meta/recipes-core/systemd/systemd_239.bb b/meta/recipes-core/systemd/systemd_239.bb
index e2dfe639b3..922ba3b57d 100644
--- a/meta/recipes-core/systemd/systemd_239.bb
+++ b/meta/recipes-core/systemd/systemd_239.bb
@@ -41,6 +41,8 @@ SRC_URI += "file://touchscreen.rules \
file://0024-journald-do-not-store-the-iovec-entry-for-process-co.patch \
file://0025-journald-set-a-limit-on-the-number-of-fields.patch \
file://0026-journal-fix-out-of-bounds-read-CVE-2018-16866.patch \
+ file://CVE-2019-6454.patch \
+ file://sd-bus-if-we-receive-an-invalid-dbus-message-ignore-.patch \
"
# patches made for musl are only applied on TCLIBC is musl
--
2.20.1
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