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From 2d197adc6d7109d5901401a90288530582f3f991 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: Tue, 26 Feb 2019 13:00:35 +0100
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Subject: [PATCH] fuzz-journal-stream: avoid assertion failure on samples which
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 don't fit in pipe
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=11587.
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We had a sample which was large enough that write(2) failed to push all the
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data into the pipe, and an assert failed. The code could be changed to use
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a loop, but then we'd need to interleave writes and sd_event_run (to process
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the journal). I don't think the complexity is worth it — fuzzing works best
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if the sample is not too huge anyway. So let's just reject samples above 64k,
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and tell oss-fuzz about this limit.
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(cherry picked from commit eafadd069c4e30ed62173123326a7237448615d1)
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Resolves: #1764560
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---
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 src/fuzz/fuzz-journald-stream.c       | 2 +-
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 src/fuzz/fuzz-journald-stream.options | 2 ++
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 2 files changed, 3 insertions(+), 1 deletion(-)
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 create mode 100644 src/fuzz/fuzz-journald-stream.options
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diff --git a/src/fuzz/fuzz-journald-stream.c b/src/fuzz/fuzz-journald-stream.c
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index 247c0889bc..693b197d3a 100644
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--- a/src/fuzz/fuzz-journald-stream.c
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+++ b/src/fuzz/fuzz-journald-stream.c
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@@ -14,7 +14,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
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         StdoutStream *stream;
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         int v;
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-        if (size == 0)
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+        if (size == 0 || size > 65536)
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                 return 0;
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         if (!getenv("SYSTEMD_LOG_LEVEL"))
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diff --git a/src/fuzz/fuzz-journald-stream.options b/src/fuzz/fuzz-journald-stream.options
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new file mode 100644
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index 0000000000..678d526b1e
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--- /dev/null
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+++ b/src/fuzz/fuzz-journald-stream.options
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@@ -0,0 +1,2 @@
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+[libfuzzer]
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+max_len = 65536