Re: [PATCH net-next v3] ipv6: Fix signed integer overflow in __ip6_append_data

[Jakub Kicinski <kuba@xxxxxxxxxx>]

On Sat, 28 May 2022 10:23:12 +0800 Wang Yufen wrote:
> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index 55afd7f39c04..91704bbc7715 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -1308,7 +1308,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>  	struct ipcm6_cookie ipc6;
>  	int addr_len = msg->msg_namelen;
>  	bool connected = false;
> -	int ulen = len;
> +	size_t ulen = len;
>  	int corkreq = READ_ONCE(up->corkflag) || msg->msg_flags&MSG_MORE;
>  	int err;
>  	int is_udplite = IS_UDPLITE(sk);

No need to change ulen neither, it will not overflow and will be
promoted to size_t when passed to ip6_append_data() / ip6_make_skb().