netdev - [PATCH bpf-next 1/1] selftests/bpf: Test changing packet data from kfunc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250926164142.1850176-1-ameryhung@gmail.com>
Date: Fri, 26 Sep 2025 09:41:42 -0700
From: Amery Hung <ameryhung@...il.com>
To: bpf@...r.kernel.org
Cc: netdev@...r.kernel.org,
	alexei.starovoitov@...il.com,
	andrii@...nel.org,
	daniel@...earbox.net,
	martin.lau@...nel.org,
	kernel-team@...a.com
Subject: [PATCH bpf-next 1/1] selftests/bpf: Test changing packet data from kfunc

bpf_xdp_pull_data() is the first kfunc that changes packet data. Make
sure the verifier clear all packet pointers after calling packet data
changing kfunc.

Signed-off-by: Amery Hung <ameryhung@...il.com>
---
 tools/testing/selftests/bpf/progs/verifier_sock.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/verifier_sock.c b/tools/testing/selftests/bpf/progs/verifier_sock.c
index b4d31f10a976..2b4610b53382 100644
--- a/tools/testing/selftests/bpf/progs/verifier_sock.c
+++ b/tools/testing/selftests/bpf/progs/verifier_sock.c
@@ -1096,6 +1096,20 @@ int invalidate_xdp_pkt_pointers_from_global_func(struct xdp_md *x)
 	return XDP_PASS;
 }
 
+/* XDP packet changing kfunc calls invalidate packet pointers */
+SEC("xdp")
+__failure __msg("invalid mem access")
+int invalidate_xdp_pkt_pointers(struct xdp_md *x)
+{
+	int *p = (void *)(long)x->data;
+
+	if ((void *)(p + 1) > (void *)(long)x->data_end)
+		return XDP_DROP;
+	bpf_xdp_pull_data(x, 0);
+	*p = 42; /* this is unsafe */
+	return XDP_PASS;
+}
+
 __noinline
 int tail_call(struct __sk_buff *sk)
 {
-- 
2.47.3