Re: [PATCH] Bluetooth: Fix type of len in rfcomm_sock_{bind,getsockopt_old}()

[Aleksei Vetrov <vvvvvv@google.com>]

Hi Andrej,

On Wed, Oct 02, 2024 at 04:12:17PM +0200, Andrej Shadura wrote:
> Change the type of len to size_t in both rfcomm_sock_bind and
> rfcomm_sock_getsockopt_old and replace min_t() with min().

rfcomm_sock_bind doesn't use copy_to_user, are you sure it has the same
issue?

> @@ -328,14 +328,15 @@ static int rfcomm_sock_bind(struct socket *sock, struct sockaddr *addr, int addr
>  {
>  	struct sockaddr_rc sa;
>  	struct sock *sk = sock->sk;
> -	int len, err = 0;
> +	int err = 0;
> +	size_t len;
>  
>  	if (!addr || addr_len < offsetofend(struct sockaddr, sa_family) ||
>  	    addr->sa_family != AF_BLUETOOTH)
>  		return -EINVAL;
>  
>  	memset(&sa, 0, sizeof(sa));
> -	len = min_t(unsigned int, sizeof(sa), addr_len);
> +	len = min(sizeof(sa), addr_len);
>  	memcpy(&sa, addr, len);
>  
>  	BT_DBG("sk %p %pMR", sk, &sa.rc_bdaddr);

This change produces a compilation error around min expression, as
"kernel test robot" notices below. And I think rfcomm_sock_bind
shouldn't be touched at all, it doesn't use copy_to_user and doesn't
produce compile errors with latest Clang.

> @@ -729,7 +730,8 @@ static int rfcomm_sock_getsockopt_old(struct socket *sock, int optname, char __u
>  	struct sock *l2cap_sk;
>  	struct l2cap_conn *conn;
>  	struct rfcomm_conninfo cinfo;
> -	int len, err = 0;
> +	int err = 0;
> +	size_t len;
>  	u32 opt;
>  
>  	BT_DBG("sk %p", sk);
> @@ -783,7 +785,7 @@ static int rfcomm_sock_getsockopt_old(struct socket *sock, int optname, char __u
>  		cinfo.hci_handle = conn->hcon->handle;
>  		memcpy(cinfo.dev_class, conn->hcon->dev_class, 3);
>  
> -		len = min_t(unsigned int, len, sizeof(cinfo));
> +		len = min(len, sizeof(cinfo));
>  		if (copy_to_user(optval, (char *) &cinfo, len))
>  			err = -EFAULT;
>  

This looks ok. But there is the same pattern in rfcomm_sock_getsockopt
(without old prefix) and it also uses copy_to_user and produces compile
error with latest Clang.

Could you remove rfcomm_sock_bind patch and apply it to
rfcomm_sock_getsockopt instead? Or I can send my version of the patch:
we've encountered the same compile errors in rfcomm_sock_getsockopt and
rfcomm_sock_getsockopt_old after updating Clang and would like to get it
fixed.