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From d212765dc94ba25c04e0e9a278586f0e86851e35 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: Sat, 11 Aug 2018 08:32:20 +0200
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Subject: [PATCH] bus-message: fix skipping of array fields in !gvariant
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 messages
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We copied part of the string into a buffer that was off by two.
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If the element signature had length one, we'd copy 0 bytes and crash when
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looking at the "first" byte. Otherwise, we would crash because strncpy would
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not terminate the string.
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(cherry picked from commit 73777ddba5100fe6c0791cd37a91f24a515f3202)
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Resolves: #1696224
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---
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 src/libsystemd/sd-bus/bus-message.c               |   8 ++++----
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 ...crash-37449529b1ad867f0c2671fa80aca5d7812a2b70 | Bin 0 -> 534 bytes
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 2 files changed, 4 insertions(+), 4 deletions(-)
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 create mode 100644 test/fuzz/fuzz-bus-message/crash-37449529b1ad867f0c2671fa80aca5d7812a2b70
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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 09e72d89dd..202f1aab30 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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@@ -4981,18 +4981,18 @@ static int message_skip_fields(
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                 } else if (t == SD_BUS_TYPE_ARRAY) {
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-                        r = signature_element_length(*signature+1, &l);
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+                        r = signature_element_length(*signature + 1, &l);
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                         if (r < 0)
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                                 return r;
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                         assert(l >= 1);
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                         {
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-                                char sig[l-1], *s;
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+                                char sig[l + 1], *s = sig;
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                                 uint32_t nas;
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                                 int alignment;
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-                                strncpy(sig, *signature + 1, l-1);
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-                                s = sig;
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+                                strncpy(sig, *signature + 1, l);
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+                                sig[l] = '\0';
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                                 alignment = bus_type_get_alignment(sig[0]);
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                                 if (alignment < 0)
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diff --git a/test/fuzz/fuzz-bus-message/crash-37449529b1ad867f0c2671fa80aca5d7812a2b70 b/test/fuzz/fuzz-bus-message/crash-37449529b1ad867f0c2671fa80aca5d7812a2b70
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new file mode 100644
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index 0000000000000000000000000000000000000000..6a20265a39e1b4a318b50aee2b13727ddc4113bf
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GIT binary patch
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literal 534
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zcmc~{WMHggWMD`aVqj=xU|>*W&P&W-;Q0Fg|9>Elfq|V9OfmRED27Bi2!jjC2Wn-|
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z17hYPAOVtNW-Ml42GVKy`9P9^ffdMS1=8h-IVt%J91NTwNgyEFV4&K>#6$*=MMgl(
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r%#fH?l1eMv=;=K=_yi-CK!KUB2_%6r0c0u^mlS2@rGxk|0FGY(dwVLU
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literal 0
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HcmV?d00001
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