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From: Leon Romanovsky <leon@kernel.org>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: "Divya Indi" <divya.indi@oracle.com>,
	linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org,
	"Kaike Wan" <kaike.wan@intel.com>,
	"Gerd Rausch" <gerd.rausch@oracle.com>,
	"Håkon Bugge" <haakon.bugge@oracle.com>,
	"Srinivas Eeda" <srinivas.eeda@oracle.com>,
	"Rama Nichanamatlu" <rama.nichanamatlu@oracle.com>,
	"Doug Ledford" <dledford@redhat.com>
Subject: Re: [PATCH v3] IB/sa: Resolving use-after-free in ib_nl_send_msg
Date: Sun, 21 Jun 2020 10:12:27 +0300	[thread overview]
Message-ID: <20200621071227.GA6698@unreal> (raw)
In-Reply-To: <20200617182300.GJ6578@ziepe.ca>

On Wed, Jun 17, 2020 at 03:23:00PM -0300, Jason Gunthorpe wrote:
> On Wed, Jun 17, 2020 at 08:17:39AM +0300, Leon Romanovsky wrote:
> >
> > My thoughts that everything here hints me that state machine and
> > locking are implemented wrongly. In ideal world, the expectation
> > is that REQ message will have a state in it (PREPARED, SENT, ACK
> > e.t.c.) and list manipulations are done accordingly with proper
> > locks, while rdma_nl_multicast() is done outside of the locks.
>
> It can't be done outside the lock without creating races - once
> rdma_nl_multicast happens it is possible for the other leg of the
> operation to begin processing.

It means that the state machine is wrong, not complete.

>
> The list must be updated before this happens.
>
> What is missing here is refcounting - the lifetime model of this data
> is too implicit, but it is not worth adding I think

I have same feeling for now, but it will flip if new fixes be in this area.

Thanks

>
> Jason

  reply	other threads:[~2020-06-21  7:12 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-08 14:46 Review Request Divya Indi
2020-06-08 14:46 ` [PATCH v3] IB/sa: Resolving use-after-free in ib_nl_send_msg Divya Indi
2020-06-09  7:00   ` Leon Romanovsky
2020-06-09 14:45     ` Divya Indi
2020-06-14  6:41       ` Leon Romanovsky
2020-06-16 17:56         ` Divya Indi
2020-06-17  5:17           ` Leon Romanovsky
2020-06-17 18:23             ` Jason Gunthorpe
2020-06-21  7:12               ` Leon Romanovsky [this message]
2020-06-17 18:24           ` Jason Gunthorpe
2020-06-20  0:43             ` Divya Indi
2020-06-09  7:03 ` Review Request Leon Romanovsky
2020-06-09 15:44   ` Divya Indi

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