From: Daniel Rosenberg <drosen@google.com>
Date: Sat, 6 May 2023 01:31:32 +0000 (-0700)
Subject: selftests/bpf: Check overflow in optional buffer
X-Git-Tag: v6.6.7~2536^2~269^2~10^2~2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3881fdfed21ff129a23979c0a92df6d3c5f49aa9;p=platform%2Fkernel%2Flinux-starfive.git

selftests/bpf: Check overflow in optional buffer

This ensures we still reject invalid memory accesses in buffers that are
marked optional.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Link: https://lore.kernel.org/r/20230506013134.2492210-4-drosen@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---

diff --git a/tools/testing/selftests/bpf/progs/dynptr_fail.c b/tools/testing/selftests/bpf/progs/dynptr_fail.c
index efe4ce7..c2f0e18 100644
--- a/tools/testing/selftests/bpf/progs/dynptr_fail.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_fail.c
@@ -1665,3 +1665,23 @@ int clone_xdp_packet_data(struct xdp_md *xdp)
 
 	return 0;
 }
+
+/* Buffers that are provided must be sufficiently long */
+SEC("?cgroup_skb/egress")
+__failure __msg("memory, len pair leads to invalid memory access")
+int test_dynptr_skb_small_buff(struct __sk_buff *skb)
+{
+	struct bpf_dynptr ptr;
+	char buffer[8] = {};
+	__u64 *data;
+
+	if (bpf_dynptr_from_skb(skb, 0, &ptr)) {
+		err = 1;
+		return 1;
+	}
+
+	/* This may return NULL. SKB may require a buffer */
+	data = bpf_dynptr_slice(&ptr, 0, buffer, 9);
+
+	return !!data;
+}