On Wed, 24 Mar 2021 22:54:42 +0100, Oliver Hartkopp wrote:
> Since commit f5223e9eee65 ("can: extend sockaddr_can to include j1939
> members") the sockaddr_can has been extended in size and a new
> CAN_REQUIRED_SIZE macro has been introduced to calculate the protocol
> specific needed size.
>
> The ABI for the msg_name and msg_namelen has not been adapted to the
> new CAN_REQUIRED_SIZE macro which leads to a problem when an existing
> binary reads the (increased) struct sockaddr_can in msg_name.
>
> Fixes: f5223e9eee65 ("can: extend sockaddr_can to include j1939 members")
> Link: https://lore.kernel.org/linux-can/1135648123.112255.1616613706554.JavaMail.zimbra@xxxxxx/T/#t
> Reported-by: Richard Weinberger <richard@xxxxxx>
> Suggested-by: Kurt Van Dijck <dev.kurt@xxxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
> ---
> net/can/bcm.c | 14 ++++++++++----
> net/can/isotp.c | 14 ++++++++++----
> net/can/raw.c | 17 +++++++++++------
> 3 files changed, 31 insertions(+), 14 deletions(-)
>
...
> @@ -808,10 +810,13 @@ static int raw_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
> int noblock;
>
> noblock = flags & MSG_DONTWAIT;
> flags &= ~MSG_DONTWAIT;
>
> + if (msg->msg_name && msg->msg_namelen < RAW_MIN_NAMELEN)
> + return -EINVAL;
> +
> if (flags & MSG_ERRQUEUE)
> return sock_recv_errqueue(sk, msg, size,
> SOL_CAN_RAW, SCM_CAN_RAW_ERRQUEUE);
>
> skb = skb_recv_datagram(sk, flags, noblock, &err);
> @@ -830,12 +835,12 @@ static int raw_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
> }
>
> sock_recv_ts_and_drops(msg, sk, skb);
>
> if (msg->msg_name) {
> - __sockaddr_check_size(sizeof(struct sockaddr_can));
> - msg->msg_namelen = sizeof(struct sockaddr_can);
> + __sockaddr_check_size(RAW_MIN_NAMELEN);
> + msg->msg_namelen = RAW_MIN_NAMELEN;
Why not fill up to MIN(msg->msg_namelen, sizeof(struct sockaddr_can))?
> memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
> }
>
> /* assign the flags that have been recorded in raw_rcv() */
> msg->msg_flags |= *(raw_flags(skb));
> --
> 2.30.2
>
