From: David Miller <davem@davemloft.net>
To: pabeni@redhat.com
Cc: netdev@vger.kernel.org, hannes@stressinduktion.org,
edumazet@google.com, mpe@ellerman.id.au,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH net-next] udp: fix poll()
Date: Fri, 23 Jun 2017 11:18:58 -0400 (EDT) [thread overview]
Message-ID: <20170623.111858.1724599210974760106.davem@davemloft.net> (raw)
In-Reply-To: <00735477ae8ffcc075e382ab45f6568ab158a0bf.1498220186.git.pabeni@redhat.com>
From: Paolo Abeni <pabeni@redhat.com>
Date: Fri, 23 Jun 2017 14:19:51 +0200
> Michael reported an UDP breakage caused by the commit b65ac44674dd
> ("udp: try to avoid 2 cache miss on dequeue").
> The function __first_packet_length() can update the checksum bits
> of the pending skb, making the scratched area out-of-sync, and
> setting skb->csum, if the skb was previously in need of checksum
> validation.
>
> On later recvmsg() for such skb, checksum validation will be
> invoked again - due to the wrong udp_skb_csum_unnecessary()
> value - and will fail, causing the valid skb to be dropped.
>
> This change addresses the issue refreshing the scratch area in
> __first_packet_length() after the possible checksum update.
>
> Fixes: b65ac44674dd ("udp: try to avoid 2 cache miss on dequeue")
> Reported-by: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Thanks for fixing this so quickly, applied.
prev parent reply other threads:[~2017-06-23 15:19 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-23 12:19 [PATCH net-next] udp: fix poll() Paolo Abeni
2017-06-23 15:18 ` David Miller [this message]
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