selftests/bpf: add a test case to check verifier pointer arithmetic

With clang/llvm 4.0+, the test case is able to generate
the following pattern:
....
440: (b7) r1 = 15
441: (05) goto pc+73
515: (79) r6 = *(u64 *)(r10 -152)
516: (bf) r7 = r10
517: (07) r7 += -112
518: (bf) r2 = r7
519: (0f) r2 += r1
520: (71) r1 = *(u8 *)(r8 +0)
521: (73) *(u8 *)(r2 +45) = r1
....

commit 332270fdc8b6 ("bpf: enhance verifier to understand stack
pointer arithmetic") improved verifier to handle such a pattern.
This patch adds a C test case to actually generate such a pattern.
A dummy tracepoint interface is used to load the program
into the kernel.

Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index 4ed049a0b14b..b59f5ed4ae40 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -268,6 +268,21 @@ out:
 	bpf_object__close(obj);
 }
 
+static void test_tcp_estats(void)
+{
+	const char *file = "./test_tcp_estats.o";
+	int err, prog_fd;
+	struct bpf_object *obj;
+	__u32 duration = 0;
+
+	err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
+	CHECK(err, "", "err %d errno %d\n", err, errno);
+	if (err)
+		return;
+
+	bpf_object__close(obj);
+}
+
 int main(void)
 {
 	struct rlimit rinf = { RLIM_INFINITY, RLIM_INFINITY };
@@ -277,6 +292,7 @@ int main(void)
 	test_pkt_access();
 	test_xdp();
 	test_l4lb();
+	test_tcp_estats();
 
 	printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt);
 	return 0;