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 20:42:12 +0200 [thread overview]
Message-ID: <1318012932.3974.7.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <1318009222.3988.28.camel@jlt3.sipsolutions.net>
On Fri, 2011-10-07 at 19:40 +0200, Johannes Berg wrote:
> > 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.
Maybe that's how you can trigger it: have one thread turn on and off
timestamping all the time, and another thread send frames all the time,
then eventually you'll probably run into the kfree_skb() case there. If
you ever manage to run into that case, it'll crash either when freeing
this skb or when freeing the original.
Anyway, it's broken. I'll stop thinking about it. You (Richard) should
fix it quickly though otherwise I think we should revert/delete this
code.
johannes
next prev parent reply other threads:[~2011-10-07 18:42 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
2011-10-07 17:47 ` Johannes Berg
2011-10-07 17:53 ` Johannes Berg
2011-10-07 18:42 ` Johannes Berg [this message]
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
2011-10-19 4:16 ` 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
2011-10-13 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
2011-10-21 10:49 ` [PATCH v2 0/3] net: time stamping fixes 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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