selftests/bpf: ksym_search won't check symbols exists

[ Upstream commit 0979ff7992fb6f4eb837995b12f4071dcafebd2d ]

Currently, ksym_search located at trace_helpers won't check symbols are
existing or not.

In ksym_search, when symbol is not found, it will return &syms[0](_stext).
But when the kernel symbols are not loaded, it will return NULL, which is
not a desired action.

This commit will add verification logic whether symbols are loaded prior
to the symbol search.

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index cabe2a3a3b30076f3bcd282758e43774bde542ec..cf156b35367985c4cf09512f7339086a1adab78d 100644 (file)
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -51,6 +51,10 @@ struct ksym *ksym_search(long key)
        int start = 0, end = sym_cnt;
        int result;
 
+       /* kallsyms not loaded. return NULL */
+       if (sym_cnt <= 0)
+               return NULL;
+
        while (start < end) {
                size_t mid = start + (end - start) / 2;