Re: [PATCH v3] IB/sa: Resolving use-after-free in ib_nl_send_msg

[Jason Gunthorpe]

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. 

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

Jason