netdev - Re: [PATCH net-next-2.6] netlink: netlink

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]

Message-ID: <1281710115.3760.27.camel@jlt3.sipsolutions.net>
Date:	Fri, 13 Aug 2010 16:35:15 +0200
From:	Johannes Berg <johannes@...solutions.net>
To:	David Miller <davem@...emloft.net>
Cc:	eric.dumazet@...il.com, netdev@...r.kernel.org
Subject: Re: [PATCH net-next-2.6] netlink: netlink_recvmsg() fix

On Fri, 2010-08-13 at 16:00 +0200, Johannes Berg wrote:
> On Sun, 2010-07-25 at 21:55 -0700, David Miller wrote:
> > From: Eric Dumazet <eric.dumazet@...il.com>
> > Date: Wed, 21 Jul 2010 10:43:55 +0200
> > 
> > > [PATCH net-next-2.6 v3] netlink: netlink_recvmsg() fix
> > > 
> > > commit 1dacc76d0014 
> > > (net/compat/wext: send different messages to compat tasks)
> > > introduced a race condition on netlink, in case MSG_PEEK is used.
> > > 
> > > An skb given by skb_recv_datagram() might be shared, we must copy it
> > > before any modification, or risk fatal corruption.
> > > 
> > > Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
> > 
> > Applied, thanks Eric.
> 
> I keep getting errors like below in 2.6.35+wireless-testing. Not saying
> that it's this patch's fault, but it is the only thing I remember
> touching that area.

In fact, I think something's wrong with this patch, since my comment
(that right now unfortunately I no longer fully understand) says:

                 * If this skb has a frag_list, then here that means that
                 * we will have to use the frag_list skb for compat tasks
                 * and the regular skb for non-compat tasks.
                 *
                 * The skb might (and likely will) be cloned, so we can't
                 * just reset frag_list and go on with things -- we need to
                 * keep that. For the compat case that's easy -- simply get
                 * a reference to the compat skb and free the regular one
                 * including the frag. For the non-compat case, we need to
                 * avoid sending the frag to the user -- so assign NULL but
                 * restore it below before freeing the skb.

and that's no longer true, afaict.

johannes


--
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