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From:   Greg Thelen <gthelen@google.com>
Date:   Fri, 30 Mar 2018 18:32:01 -0700
Message-ID: <CAHH2K0aH-dJMzR=unhBWPD7=d0RQoTK35o6U4dP+FSKj-a0WgQ@mail.gmail.com>
Subject: Re: [PATCH] RDMA/ucma: reject AF_IB ip multicast requests
To:     Doug Ledford <dledford@redhat.com>, Jason Gunthorpe <jgg@ziepe.ca>,
        Sean Hefty <sean.hefty@intel.com>
Cc:     linux-rdma@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        Greg Thelen <gthelen@google.com>
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On Thu, Mar 29, 2018 at 9:24 PM, Greg Thelen <gthelen@google.com> wrote:
> syzbot discovered that ucma_join_ip_multicast() mishandles AF_IB request
> addresses.  If an RDMA_USER_CM_CMD_JOIN_IP_MCAST request has
> cmd.addr.sa_family=AF_IB then ucma_join_ip_multicast() reads beyond the
> end of its cmd.addr.
>
> Reject non IP RDMA_USER_CM_CMD_JOIN_IP_MCAST requests.
> RDMA_USER_CM_CMD_JOIN_MCAST is interface for AF_IB multicast.
>
> And add a buffer length safety check.
>
> Fixes: 5bc2b7b397b0 ("RDMA/ucma: Allow user space to specify AF_IB when joining multicast")
> Signed-off-by: Greg Thelen <gthelen@google.com>
> ---
>  drivers/infiniband/core/ucma.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)

My patch is no longer needed.  linus/master recently picked up
84652aefb347 ("RDMA/ucma: Introduce safer rdma_addr_size() variants")
which fixes the same issue.

> diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
> index e5a1e7d81326..e410e03940ff 100644
> --- a/drivers/infiniband/core/ucma.c
> +++ b/drivers/infiniband/core/ucma.c
> @@ -1423,11 +1423,19 @@ static ssize_t ucma_join_ip_multicast(struct ucma_file *file,
>         if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
>                 return -EFAULT;
>
> +       switch (cmd.addr.sin6_family) {
> +       case AF_INET:
> +       case AF_INET6:
> +               break;
> +       default:
> +               return -EINVAL;
> +       }
> +
>         join_cmd.response = cmd.response;
>         join_cmd.uid = cmd.uid;
>         join_cmd.id = cmd.id;
>         join_cmd.addr_size = rdma_addr_size((struct sockaddr *) &cmd.addr);
> -       if (!join_cmd.addr_size)
> +       if (!join_cmd.addr_size || join_cmd.addr_size > sizeof(cmd.addr))
>                 return -EINVAL;
>
>         join_cmd.join_flags = RDMA_MC_JOIN_FLAG_FULLMEMBER;
> --
> 2.17.0.rc1.321.gba9d0f2565-goog
>