fuzz: avoid double-fetches by default

The generic fuzzer can find double-fetch bugs. However:
* We currently have no good way of producing qemu-system reproducers for
  double-fetch bugs. Even if we can get developers to run the binary-blob
  reproducers with the qemu-fuzz builds, we currently don't have a minimizer for
  these reproducers, so they are usually not easy to follow.
* Often times the fuzzer will provide a reproducer containing a
  double-fetch for a bug that can be reproduced without double-fetching.

Until we find a way to build nice double-fetch reproducers that
developers are willing to look at, lets tell OSS-Fuzz to avoid
double-fetches.

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Message-Id: <20201202164214.93867-1-alxndr@bu.edu>
Signed-off-by: Thomas Huth <thuth@redhat.com>

diff --git a/tests/qtest/fuzz/generic_fuzz.c b/tests/qtest/fuzz/generic_fuzz.c
index 262a963..07ad690 100644 (file)
--- a/tests/qtest/fuzz/generic_fuzz.c
+++ b/tests/qtest/fuzz/generic_fuzz.c
@@ -916,6 +916,7 @@ static GString *generic_fuzz_predefined_config_cmdline(FuzzTarget *t)
     g_assert(t->opaque);
 
     config = t->opaque;
+    setenv("QEMU_AVOID_DOUBLE_FETCH", "1", 1);
     setenv("QEMU_FUZZ_ARGS", config->args, 1);
     setenv("QEMU_FUZZ_OBJECTS", config->objects, 1);
     return generic_fuzz_cmdline(t);