oss-fuzz: reject giant configs early

It should help the fuzzer to avoid running into timeouts like https://oss-fuzz.com/testcase-detail/5132999948632064. Hopefully, once this is merged OSS-Fuzz will report only infinite loops as timeouts. Signed-off-by: Evgeny Vereshchagin <evvers@ya.ru>

oss-fuzz: reject giant configs early
2f593756 · Evgeny Vereshchagin · Christian Brauner · 52c57882 · 2f593756
Unverified Commit 2f593756 authored Mar 30, 2021 by Evgeny Vereshchagin Committed by Christian Brauner Apr 02, 2021
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fuzz-lxc-config-read.c src/tests/fuzz-lxc-config-read.c +7 -0

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--- a/src/tests/fuzz-lxc-config-read.c
+++ b/src/tests/fuzz-lxc-config-read.c
@@ -13,6 +13,13 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
 	char tmpf[] = "/tmp/fuzz-lxc-config-read-XXXXXX";
 	struct lxc_conf *conf = NULL;

+	/*
+	 * 100Kb should probably be enough to trigger all the issues
+	 * we're interested in without any timeouts
+	 */
+	if (size > 102400)
+		return 0;
+
 	fd = lxc_make_tmpfile(tmpf, false);
 	lxc_test_assert_abort(fd >= 0);
 	lxc_write_nointr(fd, data, size);