[PATCH AUTOSEL 5.7 52/54] bpf: selftests: global_funcs: Check err_str before strstr

[Sasha Levin]

From: Yauheni Kaliuta <yauheni.kaliuta@xxxxxxxxxx>

[ Upstream commit c210773d6c6f595f5922d56b7391fe343bc7310e ]

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@xxxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Acked-by: Yonghong Song <yhs@xxxxxx>
Link: https://lore.kernel.org/bpf/20200820115843.39454-1-yauheni.kaliuta@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 tools/testing/selftests/bpf/prog_tests/test_global_funcs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c b/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c
index 25b068591e9a4..193002b14d7f6 100644
--- 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 libbpf_print_level level,
 	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);
-- 
2.25.1