From 0045159ffd9fb174b3da5fcccb5d2139245fe089 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>

Date: Mon, 9 Jul 2018 13:21:44 +0200

Subject: [PATCH] bus-message: do not crash on message with a string of zero

 length

We'd calculate the "real" length of the string as 'item_size - 1', which does

not work out well when item_size == 0.

(cherry-picked from commit 81b6e63029eefcb0ec03a3a7c248490e38106073)

Resolves: #1643396

---

 src/libsystemd/sd-bus/bus-message.c                |   6 ++++++

 .../crash-29ed3c202e0ffade3cad42c8bbeb6cc68a21eb8e | Bin 0 -> 51 bytes

 2 files changed, 6 insertions(+)

 create mode 100644 test/fuzz/fuzz-bus-message/crash-29ed3c202e0ffade3cad42c8bbeb6cc68a21eb8e

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

index c8402a23a9..121e65674d 100644

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

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

@@ -3402,6 +3402,12 @@ _public_ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {

                 if (IN_SET(type, SD_BUS_TYPE_STRING, SD_BUS_TYPE_OBJECT_PATH, SD_BUS_TYPE_SIGNATURE)) {

                         bool ok;

+                        /* D-Bus spec: The marshalling formats for the string-like types all end

+                         * with a single zero (NUL) byte, but that byte is not considered to be part

+                         * of the text. */

+                        if (c->item_size == 0)

+                                return -EBADMSG;

+

                         r = message_peek_body(m, &rindex, 1, c->item_size, &q);

                         if (r < 0)

                                 return r;

diff --git a/test/fuzz/fuzz-bus-message/crash-29ed3c202e0ffade3cad42c8bbeb6cc68a21eb8e b/test/fuzz/fuzz-bus-message/crash-29ed3c202e0ffade3cad42c8bbeb6cc68a21eb8e

new file mode 100644

index 0000000000000000000000000000000000000000..4488f0a6c685b5d43eddbe41a0c6a3b6be9b02e2

GIT binary patch

literal 51

fcmc~1WMC4sJpJnr13KV`0|t%6q+%$@&=ddw)CUPg

literal 0

HcmV?d00001