From: Johannes Berg <johannes@sipsolutions.net>
To: David Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org, richardcochran@gmail.com
Subject: Re: [RFC] net: remove erroneous sk null assignment in timestamping
Date: Fri, 07 Oct 2011 19:40:22 +0200 [thread overview]
Message-ID: <1318009222.3988.28.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <20111007.133356.489094996618032061.davem@davemloft.net>
On Fri, 2011-10-07 at 13:33 -0400, David Miller wrote:
> From: Johannes Berg <johannes@sipsolutions.net>
> Date: Fri, 07 Oct 2011 19:11:41 +0200
>
> > From: Johannes Berg <johannes.berg@intel.com>
> >
> > skb->sk is obviously required to be non-NULL
> > when we get into skb_complete_tx_timestamp().
> > sock_queue_err_skb() will call skb_orphan()
> > first thing which sets skb->sk = NULL itself.
> > This may crash if the skb is still charged to
> > the socket (skb->destructor is sk_wfree).
> >
> > The assignment here thus seems to not only be
> > pointless (due to the skb_orphan() call) but
> > also dangerous (due to the crash).
> >
> > Signed-off-by: Johannes Berg <johannes.berg@intel.com>
>
> It looks like skb_clone_tx_timestamp() sets clone->sk without any
> proper refcounting, so I bet this NULL'ing it out is working
> around that bug.
You're right. But this bug can actually trigger another way: The only
user of this is dp83640_txtstamp() which might do kfree_skb() on this
skb, in which case that'll likely crash trying to clean up the sk.
johannes
next prev parent reply other threads:[~2011-10-07 17:40 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-07 17:11 [RFC] net: remove erroneous sk null assignment in timestamping Johannes Berg
2011-10-07 17:33 ` David Miller
2011-10-07 17:40 ` Johannes Berg [this message]
2011-10-07 17:47 ` Johannes Berg
2011-10-07 17:53 ` Johannes Berg
2011-10-07 18:42 ` Johannes Berg
2011-10-08 7:59 ` Richard Cochran
2011-10-08 7:57 ` Richard Cochran
2011-10-08 8:16 ` Johannes Berg
2011-10-08 8:57 ` Eric Dumazet
2011-10-08 10:32 ` Johannes Berg
2011-10-11 13:34 ` Richard Cochran
2011-10-08 10:35 ` Richard Cochran
2011-10-12 18:36 ` [PATCH 1/1] net: hold sock reference while processing tx timestamps Richard Cochran
2011-10-12 19:25 ` Eric Dumazet
2011-10-12 19:27 ` Johannes Berg
2011-10-12 19:52 ` Eric Dumazet
2011-10-13 8:54 ` Johannes Berg
2011-10-13 4:51 ` Richard Cochran
2011-10-13 9:46 ` [PATCH 0/3] net: time stamping fixes Richard Cochran
2011-10-13 9:46 ` [PATCH 1/3] net: hold sock reference while processing tx timestamps Richard Cochran
2011-10-19 4:42 ` Eric Dumazet
2011-10-13 9:46 ` [PATCH 2/3] dp83640: use proper function to free transmit time stamping packets Richard Cochran
2011-10-19 4:47 ` Eric Dumazet
2011-10-13 9:46 ` [PATCH 3/3] dp83640: free packet queues on remove Richard Cochran
2011-10-19 4:48 ` Eric Dumazet
2011-10-19 4:16 ` [PATCH 0/3] net: time stamping fixes David Miller
2011-10-19 5:15 ` Johannes Berg
2011-10-19 11:50 ` Richard Cochran
2011-10-19 12:33 ` Eric Dumazet
2011-10-19 12:38 ` Eric Dumazet
2011-10-19 12:58 ` Johannes Berg
2011-10-19 13:09 ` Johannes Berg
2011-10-19 13:25 ` Eric Dumazet
2011-10-19 13:35 ` Johannes Berg
2011-10-19 13:44 ` Eric Dumazet
2011-10-19 13:57 ` Johannes Berg
2011-10-19 14:08 ` Eric Dumazet
2011-10-19 14:24 ` Johannes Berg
2011-10-19 14:27 ` Richard Cochran
2011-10-19 14:33 ` Eric Dumazet
2011-10-19 13:21 ` Eric Dumazet
2011-10-19 13:25 ` Johannes Berg
2011-10-19 13:27 ` Eric Dumazet
2011-10-19 13:32 ` Johannes Berg
2011-10-19 14:25 ` Richard Cochran
2011-10-21 10:49 ` [PATCH v2 " Richard Cochran
2011-10-21 10:49 ` [PATCH v2 1/3] net: hold sock reference while processing tx timestamps Richard Cochran
2011-10-21 11:31 ` Eric Dumazet
2011-10-24 6:55 ` David Miller
2011-10-21 11:44 ` Johannes Berg
2011-10-21 10:49 ` [PATCH v2 2/3] dp83640: use proper function to free transmit time stamping packets Richard Cochran
2011-10-24 6:55 ` David Miller
2011-10-24 17:47 ` Richard Cochran
2011-10-24 23:16 ` David Miller
2011-10-21 10:49 ` [PATCH v2 3/3] dp83640: free packet queues on remove Richard Cochran
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