Re: PATCH: Breaking UAPI change?

[Richard Weinberger <richard@nod.at>]

Kurt,

----- Ursprüngliche Mail -----
> Happy testing?

;-)

 
> commit 124900109ca88d29382ef2e2b848d3a2f9d67b98
> Author: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>
> Date:   Wed Mar 24 20:08:50 2021
> 
>    can raw: don't increase provided name length
>    
>    The length of the buffer is known by the application,
>    not the kernel. Kernel is supposed to return only the
>    size of used bytes.
>    There is a minimum required size for the struct sockaddr_can
>    to be usefull for can_raw, so errors are returned when
>    the provided size is lower
>    
>    Signed-off-by: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>
> 
> diff --git a/net/can/raw.c b/net/can/raw.c
> index 6ec8aa1d0da4..00d352ae221e 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -475,7 +475,7 @@ static int raw_getname(struct socket *sock, struct sockaddr
> *uaddr,
> 	if (peer)
> 		return -EOPNOTSUPP;
> 
> -	memset(addr, 0, sizeof(*addr));
> +	memset(addr, 0, CAN_REQUIRED_SIZE(*addr, ifindex));

can_ifindex?

> 	addr->can_family  = AF_CAN;
> 	addr->can_ifindex = ro->ifindex;
> 
> @@ -806,6 +806,10 @@ static int raw_recvmsg(struct socket *sock, struct msghdr
> *msg, size_t size,
> 		return sock_recv_errqueue(sk, msg, size,
> 					  SOL_CAN_RAW, SCM_CAN_RAW_ERRQUEUE);
> 
> +	if (msg->name && msg->msg_namelen <

msg->msg_name?

> +			CAN_REQUIRED_SIZE(struct sockaddr_can, ifindex))
> +		return -EINVAL;
> +

With the above changes this -EINVAL always triggers.
msg->msg_namelen is 0 in my case.

The application does:
socklen_t addrlen = sizeof(struct sockaddr_can);
recvfrom(s, &frame, sizeof(struct can_frame), 0, (struct sockaddr *)&addr, &addrlen);

Thanks,
//richard