netdev - Re: [PATCH net-next 09/11] tcp: Check for filled TCP option space before SACK

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Message-ID: <alpine.OSX.2.21.1912131607000.38100@amhui-mobl1.amr.corp.intel.com>
Date:   Fri, 13 Dec 2019 16:28:46 -0800 (PST)
From:   Mat Martineau <mathew.j.martineau@...ux.intel.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
cc:     netdev@...r.kernel.org, mptcp@...ts.01.org
Subject: Re: [PATCH net-next 09/11] tcp: Check for filled TCP option space
 before SACK

On Fri, 13 Dec 2019, Eric Dumazet wrote:

>
>
> On 12/13/19 3:00 PM, Mat Martineau wrote:
>> The SACK code would potentially add four bytes to the expected
>> TCP option size even if all option space was already used.
>>
>> Signed-off-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
>> ---
>>  net/ipv4/tcp_output.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
>> index 9e04d45bc0e4..710ab45badfa 100644
>> --- a/net/ipv4/tcp_output.c
>> +++ b/net/ipv4/tcp_output.c
>> @@ -748,6 +748,9 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
>>  		size += TCPOLEN_TSTAMP_ALIGNED;
>>  	}
>>
>> +	if (size + TCPOLEN_SACK_BASE_ALIGNED >= MAX_TCP_OPTION_SPACE)
>> +		return size;
>> +
>>  	eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack;
>>  	if (unlikely(eff_sacks)) {
>>  		const unsigned int remaining = MAX_TCP_OPTION_SPACE - size;
>>
>
>
> Hmmm... I thought I already fixed this issue ?
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9424e2e7ad93ffffa88f882c9bc5023570904b55
>
> Please do not mix fixes (targeting net tree) in a patch series targeting net-next

Ok, good that it is already fixed. We have tried to upstream generic fixes 
when they're identified but obviously misclassified this one.

--
Mat Martineau
Intel