From 2d197adc6d7109d5901401a90288530582f3f991 Mon Sep 17 00:00:00 2001

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

Date: Tue, 26 Feb 2019 13:00:35 +0100

Subject: [PATCH] fuzz-journal-stream: avoid assertion failure on samples which

 don't fit in pipe

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Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=11587.

We had a sample which was large enough that write(2) failed to push all the

data into the pipe, and an assert failed. The code could be changed to use

a loop, but then we'd need to interleave writes and sd_event_run (to process

the journal). I don't think the complexity is worth it — fuzzing works best

if the sample is not too huge anyway. So let's just reject samples above 64k,

and tell oss-fuzz about this limit.

(cherry picked from commit eafadd069c4e30ed62173123326a7237448615d1)

Resolves: #1764560

---

 src/fuzz/fuzz-journald-stream.c       | 2 +-

 src/fuzz/fuzz-journald-stream.options | 2 ++

 2 files changed, 3 insertions(+), 1 deletion(-)

 create mode 100644 src/fuzz/fuzz-journald-stream.options

diff --git a/src/fuzz/fuzz-journald-stream.c b/src/fuzz/fuzz-journald-stream.c

index 247c0889bc..693b197d3a 100644

--- a/src/fuzz/fuzz-journald-stream.c

+++ b/src/fuzz/fuzz-journald-stream.c

@@ -14,7 +14,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {

         StdoutStream *stream;

         int v;

-        if (size == 0)

+        if (size == 0 || size > 65536)

                 return 0;

         if (!getenv("SYSTEMD_LOG_LEVEL"))

diff --git a/src/fuzz/fuzz-journald-stream.options b/src/fuzz/fuzz-journald-stream.options

new file mode 100644

index 0000000000..678d526b1e

--- /dev/null

+++ b/src/fuzz/fuzz-journald-stream.options

@@ -0,0 +1,2 @@

+[libfuzzer]

+max_len = 65536