Re: [PATCH bpf-next v5 3/4] selftests/bpf: add bpf_icmp_send kfunc IPv6 tests

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Buffer truncation and type confusion when calling getsockname() for IPv6 sockets.
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commit 3f16e831f177058fc11380fe48e08f94594b83bf
Author: Mahe Tardy <mahe.tardy@gmail.com>

selftests/bpf: add bpf_icmp_send kfunc IPv6 tests

This commit extends the existing bpf_icmp_send kfunc tests with IPv6
support. It updates the test suite to handle IPv6 connections and
ICMPv6 error queues.

> diff --git a/tools/testing/selftests/bpf/prog_tests/icmp_send_kfunc.c b/tools/testing/selftests/bpf/prog_tests/icmp_send_kfunc.c
> index b98c0312adadc..d9badfc6e620c 100644
> --- a/tools/testing/selftests/bpf/prog_tests/icmp_send_kfunc.c
> +++ b/tools/testing/selftests/bpf/prog_tests/icmp_send_kfunc.c

[ ... ]

> @@ -78,14 +92,13 @@ static void read_icmp_errqueue(int sockfd, int expected_code)
>  }
>  
>  static void trigger_prog_read_icmp_errqueue(struct icmp_send *skel,
> -					    int code)
> +					    int code, int af, const char *ip)
>  {
>  	int srv_fd = -1, client_fd = -1;
>  	struct sockaddr_in addr;
>  	socklen_t len = sizeof(addr);
>  
> -	srv_fd = start_server(AF_INET, SOCK_STREAM, "127.0.0.1", 0,
> -			      TIMEOUT_MS);
> +	srv_fd = start_server(af, SOCK_STREAM, ip, 0, TIMEOUT_MS);
>  	if (!ASSERT_GE(srv_fd, 0, "start_server"))
>  		return;
>  
> @@ -94,6 +107,8 @@ static void trigger_prog_read_icmp_errqueue(struct icmp_send *skel,
>  		return;
>  	}
>  	skel->bss->server_port = ntohs(addr.sin_port);

When af is AF_INET6, start_server() creates an IPv6 socket, but addr
is hardcoded as struct sockaddr_in which is 16 bytes.

Does this cause getsockname() to silently truncate the 28-byte
sockaddr_in6 structure because len is initialized to sizeof(addr)?

While reading addr.sin_port happens to work because sin_port and sin6_port
share the same offset, would it be better to use struct sockaddr_storage 
here (like in connect_to_fd_nonblock() earlier in the file) and extract
the port conditionally based on the address family to avoid type confusion?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260515194746.50920-1-mahe.tardy@gmail.com?part=3