netdev - Re: [PATCH v2 01/18] netlink: make the check for "send from tx

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 02 Feb 2015 16:14:16 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Al Viro <viro@...IV.linux.org.uk>,
	David Miller <davem@...emloft.net>
CC:	netdev@...r.kernel.org
Subject: Re: [PATCH v2 01/18] netlink: make the check for "send from tx_ring"
 deterministic

Hello.

On 2/2/2015 10:59 AM, Al Viro wrote:

> From: Al Viro <viro@...iv.linux.org.uk>

> As it is, zero msg_iovlen means that the first iovec in the kernel
> array of iovecs is left uninitialized, so checking if its ->iov_base
> is NULL is random.  Since the real users of that thing are doing
> sendto(fd, NULL, 0, ...), they are getting msg_iovlen = 1 and
> msg_iov[0] = {NULL, 0}, which is what this test is trying to catch.
> As suggested by davem, let's just check that msg_iovlen was 1 and
> msg_iov[0].iov_base was NULL - _that_ is well-defined and it catches
> what we want to catch.

> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
> ---
>   net/netlink/af_netlink.c | 4 ++++
>   1 file changed, 4 insertions(+)

> diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
> index a36777b..af51d58 100644
> --- a/net/netlink/af_netlink.c
> +++ b/net/netlink/af_netlink.c
> @@ -2298,7 +2298,11 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
>   			goto out;
>   	}
>
> +        /* It's a really convoluted way for userland to ask for mmaped
> +	 * sendmsg(), but that's what we've got...  */

    Hmm, not sure why DaveM hasn't commented on this broken comment formatting 
(perhaps he was going to fix it while applying?). The preferred comment style 
in the networking code is:

/* bla
  * bla
  */

WBR, Sergei

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html