From 48c76518d12e4bd504dec62fa063feb53e44235a Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 27 Jul 2018 12:08:46 +0200 Subject: [PATCH] net: merge CVE-2018-5390 patch PD#172028 merge CVE patch tcp: detect malicious patterns in tcp_collapse_ofo_queue() [ Upstream commit 3d4bf93ac12003f9b8e1e2de37fe27983deebdcf ] In case an attacker feeds tiny packets completely out of order, tcp_collapse_ofo_queue() might scan the whole rb-tree, performing expensive copies, but not changing socket memory usage at all. 1) Do not attempt to collapse tiny skbs. 2) Add logic to exit early when too many tiny skbs are detected. We prefer not doing aggressive collapsing (which copies packets) for pathological flows, and revert to tcp_prune_ofo_queue() which will be less expensive. In the future, we might add the possibility of terminating flows that are proven to be malicious. Change-Id: I5f857fe551726fcc5144cf0e217362ba0b8d85ae Signed-off-by: Eric Dumazet Acked-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_input.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 7a3b9d8e..17d88e4 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4909,6 +4909,7 @@ end: static void tcp_collapse_ofo_queue(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); + u32 range_truesize, sum_tiny = 0; struct sk_buff *skb, *head; struct rb_node *p; u32 start, end; @@ -4927,6 +4928,7 @@ new_range: } start = TCP_SKB_CB(skb)->seq; end = TCP_SKB_CB(skb)->end_seq; + range_truesize = skb->truesize; for (head = skb;;) { skb = tcp_skb_next(skb, NULL); @@ -4937,11 +4939,20 @@ new_range: if (!skb || after(TCP_SKB_CB(skb)->seq, end) || before(TCP_SKB_CB(skb)->end_seq, start)) { - tcp_collapse(sk, NULL, &tp->out_of_order_queue, - head, skb, start, end); + /* Do not attempt collapsing tiny skbs */ + if (range_truesize != head->truesize || + end - start >= SKB_WITH_OVERHEAD(SK_MEM_QUANTUM)) { + tcp_collapse(sk, NULL, &tp->out_of_order_queue, + head, skb, start, end); + } else { + sum_tiny += range_truesize; + if (sum_tiny > sk->sk_rcvbuf >> 3) + return; + } goto new_range; } + range_truesize += skb->truesize; if (unlikely(before(TCP_SKB_CB(skb)->seq, start))) start = TCP_SKB_CB(skb)->seq; if (after(TCP_SKB_CB(skb)->end_seq, end)) -- 2.7.4