From: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Date: Thu, 20 Aug 2020 14:58:43 +0300
Subject: bpf: selftests: global_funcs: Check err_str before strstr
Patch-mainline: v5.9-rc2
Git-commit: c210773d6c6f595f5922d56b7391fe343bc7310e
References: bsc#1177028

The error path in libbpf.c:load_program() has calls to pr_warn()
which ends up for global_funcs tests to
test_global_funcs.c:libbpf_debug_print().

For the tests with no struct test_def::err_str initialized with a
string, it causes call of strstr() with NULL as the second argument
and it segfaults.

Fix it by calling strstr() only for non-NULL err_str.

Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200820115843.39454-1-yauheni.kaliuta@redhat.com
Acked-by: Gary Lin <glin@suse.com>
---
 tools/testing/selftests/bpf/prog_tests/test_global_funcs.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c
@@ -19,7 +19,7 @@ static int libbpf_debug_print(enum libbp
 	log_buf = va_arg(args, char *);
 	if (!log_buf)
 		goto out;
-	if (strstr(log_buf, err_str) == 0)
+	if (err_str && strstr(log_buf, err_str) == 0)
 		found = true;
 out:
 	printf(format, log_buf);