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From: Mat Martineau <mathew.j.martineau@linux.intel.com>
To: Paolo Abeni <pabeni@redhat.com>
Cc: mptcp@lists.linux.dev
Subject: Re: [PATCH mptcp 1/2] mptcp: fix possible divide by zero
Date: Fri, 20 Aug 2021 10:53:14 -0700 (PDT)	[thread overview]
Message-ID: <cba97261-387-4bc-c453-478acab49a21@linux.intel.com> (raw)
In-Reply-To: <286de8f451b32f60e75d3b8bcc4df515e186b930.1629481305.git.pabeni@redhat.com>


On Fri, 20 Aug 2021, Paolo Abeni wrote:

> Florian noted that if mptcp_alloc_tx_skb() allocation fails
> in __mptcp_push_pending(), we can end-up invoking
> mptcp_push_release()/tcp_push() with a zero mss, causing
> a divide by 0 error.
>

I'll start running this in syzkaller now and then follow up later with 
review comments - thanks!


- Mat

> This change addresses the issue refactoring the skb allocation
> code so that skb allocation always happens after the call
> to tcp_send_mss() correctly initialize mss_now.
>
> As side bonuses we now fill the skb tx cache only when needed,
> and this also clean-up a bit the output path.
>
> Reported-by: Florian Westphal <fw@strlen.de>
> Fixes: 724cfd2ee8aa ("mptcp: allocate TX skbs in msk context")
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> ---
> net/mptcp/protocol.c | 63 ++++++++++++++++++++------------------------
> 1 file changed, 28 insertions(+), 35 deletions(-)

--
Mat Martineau
Intel

  reply	other threads:[~2021-08-20 17:53 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-20 17:44 [PATCH mptcp 0/2] mptcp: a couple of fix - almost Paolo Abeni
2021-08-20 17:44 ` [PATCH mptcp 1/2] mptcp: fix possible divide by zero Paolo Abeni
2021-08-20 17:53   ` Mat Martineau [this message]
2021-08-24  7:28   ` Matthieu Baerts
2021-08-20 17:44 ` [PATCH mptcp 2/2] mptcp: make the locking tx schema more readable Paolo Abeni
2021-08-20 23:02 ` [PATCH mptcp 0/2] mptcp: a couple of fix - almost Mat Martineau
2021-08-23  7:16   ` Matthieu Baerts

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