Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1258341

Re: [RFC] unix: fix use-after-free in unix_dgram_poll()

Show all headers | View raw

On 10/28/2015 12:46 PM, Rainer Weikusat wrote:
> Rainer Weikusat <rw@doppelsaurus.mobileactivedefense.com> writes:
>> Jason Baron <jbaron@akamai.com> writes:
> 
> [...]
> 
>>> 2)
>>>
>>> For the case of epoll() in edge triggered mode we need to ensure that
>>> when we return -EAGAIN from unix_dgram_sendmsg() when unix_recvq_full()
>>> is true, we need to add a unix_peer_wake_connect() call to guarantee a
>>> wakeup. Otherwise, we are going to potentially hang there.
>>
>> I consider this necessary.
> 
> (As already discussed privately) just doing this would open up another
> way for sockets to be enqueued on the peer_wait queue of the peer
> forever despite no one wants to be notified of write space
> availability. Here's another RFC patch addressing the issues so far plus
> this one by breaking the connection to the peer socket from the wake up
> relaying function. This has the nice additional property that the
> dgram_poll code becomes somewhat simpler as the "dequeued where we
> didn't enqueue" situation can no longer occur and the not-so-nice
> additional property that the connect and disconnect functions need to
> take the peer_wait.lock spinlock explicitly so that this lock is used to
> ensure that no two threads modifiy the private pointer of the client
> wait_queue_t.

Hmmm...I thought these were already all guarded by unix_state_lock(sk).
In any case, rest of the patch overall looks good to me.

Thanks,

-Jason

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: [PATCH v2 1/3] unix: fix use-after-free in unix_dgram_poll() Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2015-10-18 23:10 +0200
  Re: [PATCH v2 1/3] unix: fix use-after-free in unix_dgram_poll() Jason Baron <jbaron@akamai.com> - 2015-10-19 17:10 +0200
    Re: [PATCH v2 1/3] unix: fix use-after-free in unix_dgram_poll() Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2015-10-21 00:40 +0200
      Re: [PATCH v2 1/3] unix: fix use-after-free in unix_dgram_poll() Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2015-10-21 19:40 +0200
      [RFC] unix: fix use-after-free in unix_dgram_poll() Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2015-10-28 17:50 +0100
        Re: [RFC] unix: fix use-after-free in unix_dgram_poll() Jason Baron <jbaron@akamai.com> - 2015-10-28 19:00 +0100
          Re: [RFC] unix: fix use-after-free in unix_dgram_poll() Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2015-10-29 15:30 +0100
        Re: [RFC] unix: fix use-after-free in unix_dgram_poll()/ 4.2.5 Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2015-10-30 22:00 +0100

csiph-web