netdev - Re: [PATCH stable 4.4 0/9] fix SegmentSmack in stable branch (CVE-2018-5390)

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Date:   Thu, 16 Aug 2018 15:39:14 +0800
From:   maowenan <maowenan@...wei.com>
To:     Michal Kubecek <mkubecek@...e.cz>
CC:     <dwmw2@...radead.org>, <gregkh@...ux-foundation.org>,
        <netdev@...r.kernel.org>, <eric.dumazet@...il.com>,
        <edumazet@...gle.com>, <davem@...emloft.net>, <ycheng@...gle.com>,
        <jdw@...zon.de>, <stable@...r.kernel.org>,
        Takashi Iwai <tiwai@...e.de>
Subject: Re: [PATCH stable 4.4 0/9] fix SegmentSmack in stable branch
 (CVE-2018-5390)



On 2018/8/16 15:23, Michal Kubecek wrote:
> On Thu, Aug 16, 2018 at 03:19:12PM +0800, maowenan wrote:
>> On 2018/8/16 14:52, Michal Kubecek wrote:
>>>
>>> My point is that backporting all this into stable 4.4 is quite intrusive
>>> so that if we can achieve similar results with a simple fix of an
>>> obvious omission, it would be preferrable.
>>
>> There are five patches in mainline to fix this CVE, only two patches
>> have no effect on stable 4.4, the important reason is 4.4 use simple
>> queue but mainline use RB tree.
>>
>> I have tried my best to use easy way to fix this with dropping packets
>> 12.5%(or other value) based on simple queue, but the result is not
>> very well, so the RB tree is needed and tested result is my desire.
>>
>> If we only back port two patches but they don't fix the issue, I think
>> they don't make any sense.
> 
> There is an obvious omission in one of the two patches and Takashi's
> patch fixes it. If his follow-up fix (applied on top of what is in
> stable 4.4 now) addresses the problem, I would certainly prefer using it
> over backporting the whole series.

Do you mean below codes from Takashi can fix this CVE?
But I have already tested like this two days ago, it is not good effect.

Could you try to test with POC programme mentioned previous mail in case I made mistake?

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 4a261e078082..9c4c6cd0316e 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4835,6 +4835,7 @@ static void tcp_collapse_ofo_queue(struct sock *sk)
 			end = TCP_SKB_CB(skb)->end_seq;
 			range_truesize = skb->truesize;
 		} else {
+			range_truesize += skb->truesize;
 			if (before(TCP_SKB_CB(skb)->seq, start))
 				start = TCP_SKB_CB(skb)->seq;
 			if (after(TCP_SKB_CB(skb)->end_seq, end))
-- 


> 
> Michal Kubecek
> 
> 
> .
>