bpf: selftests: global_funcs: Check err_str before strstr

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

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 25b068591e9a40a42a5e62a4613f05b2081e2e77..193002b14d7f66ac9c1b6942f79d662760278ac7 100644 (file)
--- 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);