Re: [PATCH bpf-next v5 2/4] selftests/bpf: add bpf_icmp_send kfunc tests

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The `read_icmp_errqueue` function will silently pass without asserting the error code if an `IP_RECVERR` control message is not found.
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commit 30b471fdde74d100ff073064731c793e5f178384
Author: Mahe Tardy <mahe.tardy@gmail.com>

selftests/bpf: add bpf_icmp_send kfunc tests

This commit adds a new selftest for the bpf_icmp_send kfunc. It sets up
a client/server connection, attaches an egress cgroup_skb program to
trigger an ICMP unreach message, and verifies the correct ICMP unreach
code is received in the error queue.

> diff --git a/tools/testing/selftests/bpf/prog_tests/icmp_send_kfunc.c b/tools/testing/selftests/bpf/prog_tests/icmp_send_kfunc.c
> new file mode 100644
> index 0000000000000..b98c0312adadc
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/icmp_send_kfunc.c

[ ... ]

> +static void read_icmp_errqueue(int sockfd, int expected_code)
> +{

[ ... ]

> +	for (; cm; cm = CMSG_NXTHDR(&msg, cm)) {
> +		if (cm->cmsg_level != IPPROTO_IP ||
> +		    cm->cmsg_type != IP_RECVERR)
> +			continue;
> +
> +		sock_err = (struct sock_extended_err *)CMSG_DATA(cm);
> +
> +		if (!ASSERT_EQ(sock_err->ee_origin, SO_EE_ORIGIN_ICMP,
> +			       "sock_err_origin_icmp"))
> +			return;
> +		if (!ASSERT_EQ(sock_err->ee_type, ICMP_DEST_UNREACH,
> +			       "sock_err_type_dest_unreach"))
> +			return;
> +		ASSERT_EQ(sock_err->ee_code, expected_code, "sock_err_code");
> +	}
> +}

Does this function silently pass if no IP_RECVERR control message is found?

Looking at the loop, if it finishes without finding a message where
cm->cmsg_level == IPPROTO_IP and cm->cmsg_type == IP_RECVERR, it exits
normally without executing the assertions.

Should there be a check after the loop or a boolean flag used to ensure the
expected message was actually received, rather than allowing the test to
pass successfully when the message is completely absent?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260515194746.50920-1-mahe.tardy@gmail.com?part=2