On 2018/8/16 15:44, Michal Kubecek wrote:

On Thu, Aug 16, 2018 at 03:39:14PM +0800, maowenan wrote:

quoted

On 2018/8/16 15:23, Michal Kubecek wrote:

quoted

On Thu, Aug 16, 2018 at 03:19:12PM +0800, maowenan wrote:

quoted

On 2018/8/16 14:52, Michal Kubecek wrote:

quoted

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.

IIRC what you proposed was different, you proposed to replace the "=" in
the other branch by "+=".

No, I think you don't get what I mean, I have already tested stable 4.4,
based on commit dc6ae4d, and change the codes like Takashi, which didn't
contain any codes I have sent in this patch series.

I suggest someone to test again based on Takashi.

dc6ae4d tcp: detect malicious patterns in tcp_collapse_ofo_queue()
5fbec48 tcp: avoid collapses in tcp_prune_queue() if possible
255924e tcp: do not delay ACK in DCTCP upon CE status change
0b1d40e tcp: do not cancel delay-AcK on DCTCP special ACK
17fea38e7 tcp: helpers to send special DCTCP ack
500e03f tcp: fix dctcp delayed ACK schedule
b04c9a0 rtnetlink: add rtnl_link_state check in rtnl_configure_link
73dad08 net/mlx4_core: Save the qpn from the input modifier in RST2INIT wrapper
48f41c0 ip: hash fragments consistently
54a634c MIPS: ath79: fix register address in ath79_ddr_wb_flush()
762b585 Linux 4.4.144

Michal Kubecek

quoted

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))

-- 


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> Michal Kubecek
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