netdev - Re: [bpf PATCH v2 0/3] sockmap error path fixes

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Date:   Wed, 2 May 2018 15:34:03 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     John Fastabend <john.fastabend@...il.com>
Cc:     borkmann@...earbox.net, ast@...nel.org, netdev@...r.kernel.org
Subject: Re: [bpf PATCH v2 0/3] sockmap error path fixes

On Wed, May 02, 2018 at 01:50:14PM -0700, John Fastabend wrote:
> When I added the test_sockmap to selftests I mistakenly changed the
> test logic a bit. The result of this was on redirect cases we ended up
> choosing the wrong sock from the BPF program and ended up sending to a
> socket that had no receive handler. The result was the actual receive
> handler, running on a different socket, is timing out and closing the
> socket. This results in errors (-EPIPE to be specific) on the sending
> side. Typically happening if the sender does not complete the send
> before the receive side times out. So depending on timing and the size
> of the send we may get errors. This exposed some bugs in the sockmap
> error path handling.
> 
> This series fixes the errors. The primary issue is we did not do proper
> memory accounting in these cases which resulted in missing a
> sk_mem_uncharge(). This happened in the redirect path and in one case
> on the normal send path. See the three patches for the details.
> 
> The other take-away from this is we need to fix the test_sockmap and
> also add more negative test cases. That will happen in bpf-next.
> 
> Finally, I tested this using the existing test_sockmap program, the
> older sockmap sample test script, and a few real use cases with
> Cilium. All of these seem to be in working correctly.
> 
> v2: fix compiler warning, drop iterator variable 'i' that is no longer
>     used in patch 3.

Applied, Thanks.