From: Michal Luczaj <mhal@rbox.co>
Date: Tue, 14 Apr 2026 14:13:17 +0000 (+0200)
Subject: selftests/bpf: Extend bpf_iter_unix to attempt deadlocking
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=997b8483d44c60805c71a9882376a16eb176cb24;p=thirdparty%2Fkernel%2Flinux.git

selftests/bpf: Extend bpf_iter_unix to attempt deadlocking

Updating a sockmap from a unix iterator prog may lead to a deadlock.
Piggyback on the original selftest.

Signed-off-by: Michal Luczaj <mhal@rbox.co>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260414-unix-proto-update-null-ptr-deref-v4-3-2af6fe97918e@rbox.co
---

diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_unix.c b/tools/testing/selftests/bpf/progs/bpf_iter_unix.c
index fea275df9e229..a2652c8c3616f 100644
--- a/tools/testing/selftests/bpf/progs/bpf_iter_unix.c
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_unix.c
@@ -7,6 +7,13 @@
 
 char _license[] SEC("license") = "GPL";
 
+SEC(".maps") struct {
+	__uint(type, BPF_MAP_TYPE_SOCKMAP);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u64);
+} sockmap;
+
 static long sock_i_ino(const struct sock *sk)
 {
 	const struct socket *sk_socket = sk->sk_socket;
@@ -76,5 +83,8 @@ int dump_unix(struct bpf_iter__unix *ctx)
 
 	BPF_SEQ_PRINTF(seq, "\n");
 
+	/* Test for deadlock. */
+	bpf_map_update_elem(&sockmap, &(int){0}, sk, 0);
+
 	return 0;
 }