selftests/bpf: Add test to access const void pointer argument in tracing program

Adding verifier test for accessing const void pointer argument in
tracing programs.

The test program loads 1st argument of bpf_fentry_test10 function
which is const void pointer and checks that verifier allows that.

Signed-off-by: KaFai Wan <mannkafai@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20250423121329.3163461-3-mannkafai@gmail.com

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 7cb192cbd65f322baf11882adaee27adaacb4820..aaf13a7d58eda25d52b88e1b457be0350af9ceea 100644 (file)
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -569,6 +569,11 @@ __bpf_kfunc u32 bpf_fentry_test9(u32 *a)
        return *a;
 }
 
+int noinline bpf_fentry_test10(const void *a)
+{
+       return (long)a;
+}
+
 void noinline bpf_fentry_test_sinfo(struct skb_shared_info *sinfo)
 {
 }
@@ -699,7 +704,8 @@ int bpf_prog_test_run_tracing(struct bpf_prog *prog,
                    bpf_fentry_test6(16, (void *)17, 18, 19, (void *)20, 21) != 111 ||
                    bpf_fentry_test7((struct bpf_fentry_test_t *)0) != 0 ||
                    bpf_fentry_test8(&arg) != 0 ||
-                   bpf_fentry_test9(&retval) != 0)
+                   bpf_fentry_test9(&retval) != 0 ||
+                   bpf_fentry_test10((void *)0) != 0)
                        goto out;
                break;
        case BPF_MODIFY_RETURN:

diff --git a/tools/testing/selftests/bpf/progs/verifier_btf_ctx_access.c b/tools/testing/selftests/bpf/progs/verifier_btf_ctx_access.c
index 28b939572cdadf2e3f0a19400629335921040bf6..03942cec07e56b6ae9f75670f2ff4e72a4938e24 100644 (file)
--- a/tools/testing/selftests/bpf/progs/verifier_btf_ctx_access.c
+++ b/tools/testing/selftests/bpf/progs/verifier_btf_ctx_access.c
@@ -65,4 +65,16 @@ __naked void ctx_access_u32_pointer_reject_8(void)
 "      ::: __clobber_all);
 }
 
+SEC("fentry/bpf_fentry_test10")
+__description("btf_ctx_access const void pointer accept")
+__success __retval(0)
+__naked void ctx_access_const_void_pointer_accept(void)
+{
+       asm volatile ("                                 \
+       r2 = *(u64 *)(r1 + 0);          /* load 1st argument value (const void pointer) */\
+       r0 = 0;                                         \
+       exit;                                           \
+"      ::: __clobber_all);
+}
+
 char _license[] SEC("license") = "GPL";