From: Thomas Graf <tgraf@suug.ch>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>,
dborkman@redhat.com, luto@amacapital.net,
torvalds@linux-foundation.org, kaber@trash.net,
netdev@vger.kernel.org
Subject: Re: Netlink mmap tx security?
Date: Wed, 17 Dec 2014 16:26:46 +0000 [thread overview]
Message-ID: <20141217162646.GB28766@casper.infradead.org> (raw)
In-Reply-To: <1418774579.9773.69.camel@edumazet-glaptop2.roam.corp.google.com>
On 12/16/14 at 04:02pm, Eric Dumazet wrote:
> On Tue, 2014-12-16 at 17:58 -0500, David Miller wrote:
>
> > + __skb_put(skb, nm_len);
> > + memcpy(skb->data, (void *)hdr + NL_MMAP_HDRLEN, nm_len);
> > + netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);
> >
>
> Not related to this patch, but it looks like netlink_set_status()
> barrier is wrong ?
>
> It seems we need smp_wmb() after the memcpy() and before the
> hdr->nm_status = status;
Yes, definitely wrong as-is. I'll send a patch. For the particular
case we'd need a smp_rmb() after the memcpy() to complete the loads.
The skb destructor needs a smp_wmb() after setting nm_len. We could
get away with a smp_wmb() first thing in netlink_set_status() with
the code as-is but smp_mb() might be the less fragile thing to do.
Objections?
next prev parent reply other threads:[~2014-12-17 16:26 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CALCETrWsCqy7KEKPTOeHjrO1c2JE1E_seO_J+yA=sYFhS11NXQ@mail.gmail.com>
2014-05-12 21:08 ` Netlink mmap tx security? Andy Lutomirski
2014-10-11 22:29 ` Andy Lutomirski
2014-10-11 23:09 ` David Miller
2014-10-14 19:19 ` David Miller
2014-10-14 19:33 ` Andy Lutomirski
2014-10-14 20:00 ` David Miller
2014-10-14 22:16 ` Andy Lutomirski
2014-10-15 2:01 ` David Miller
2014-10-15 2:03 ` Andy Lutomirski
2014-10-15 2:09 ` David Miller
2014-10-16 6:45 ` Daniel Borkmann
2014-10-16 7:07 ` Thomas Graf
2014-12-16 22:58 ` David Miller
2014-12-16 23:58 ` Daniel Borkmann
2014-12-17 16:27 ` Thomas Graf
2014-12-18 17:36 ` David Miller
2014-12-17 0:02 ` Eric Dumazet
2014-12-17 16:26 ` Thomas Graf [this message]
2014-12-18 10:30 ` [PATCH net] netlink: Don't reorder loads/stores before marking mmap netlink frame as available Thomas Graf
2014-12-18 17:36 ` David Miller
2014-12-18 19:13 ` Linus Torvalds
2014-10-15 23:45 ` Netlink mmap tx security? Daniel Borkmann
2014-10-15 23:57 ` David Miller
2014-10-15 23:58 ` Andy Lutomirski
2014-10-16 3:34 ` David Miller
2014-10-16 5:52 ` Thomas Graf
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