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Blame SOURCES/0690-bus-message-do-not-crash-on-message-with-a-string-of.patch

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From 0045159ffd9fb174b3da5fcccb5d2139245fe089 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
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Date: Mon, 9 Jul 2018 13:21:44 +0200
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Subject: [PATCH] bus-message: do not crash on message with a string of zero
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 length
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We'd calculate the "real" length of the string as 'item_size - 1', which does
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not work out well when item_size == 0.
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(cherry-picked from commit 81b6e63029eefcb0ec03a3a7c248490e38106073)
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Resolves: #1643396
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---
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 src/libsystemd/sd-bus/bus-message.c                |   6 ++++++
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 .../crash-29ed3c202e0ffade3cad42c8bbeb6cc68a21eb8e | Bin 0 -> 51 bytes
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 2 files changed, 6 insertions(+)
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 create mode 100644 test/fuzz/fuzz-bus-message/crash-29ed3c202e0ffade3cad42c8bbeb6cc68a21eb8e
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diff --git a/src/libsystemd/sd-bus/bus-message.c b/src/libsystemd/sd-bus/bus-message.c
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index c8402a23a9..121e65674d 100644
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--- a/src/libsystemd/sd-bus/bus-message.c
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+++ b/src/libsystemd/sd-bus/bus-message.c
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@@ -3402,6 +3402,12 @@ _public_ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
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                 if (IN_SET(type, SD_BUS_TYPE_STRING, SD_BUS_TYPE_OBJECT_PATH, SD_BUS_TYPE_SIGNATURE)) {
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                         bool ok;
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+                        /* D-Bus spec: The marshalling formats for the string-like types all end
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+                         * with a single zero (NUL) byte, but that byte is not considered to be part
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+                         * of the text. */
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+                        if (c->item_size == 0)
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+                                return -EBADMSG;
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+
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                         r = message_peek_body(m, &rindex, 1, c->item_size, &q);
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                         if (r < 0)
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                                 return r;
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diff --git a/test/fuzz/fuzz-bus-message/crash-29ed3c202e0ffade3cad42c8bbeb6cc68a21eb8e b/test/fuzz/fuzz-bus-message/crash-29ed3c202e0ffade3cad42c8bbeb6cc68a21eb8e
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new file mode 100644
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index 0000000000000000000000000000000000000000..4488f0a6c685b5d43eddbe41a0c6a3b6be9b02e2
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GIT binary patch
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literal 51
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fcmc~1WMC4sJpJnr13KV`0|t%6q+%$@&=ddw)CUPg
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literal 0
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HcmV?d00001
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