From 87922b7adc47f311e89b21e37b26ee300a401e1d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= 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: #1635439 --- 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 8d92bc2002..381034f5f8 100644 --- a/src/libsystemd/sd-bus/bus-message.c +++ b/src/libsystemd/sd-bus/bus-message.c @@ -3312,6 +3312,12 @@ _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