From: Peter Oskolkov <posk@google.com>
Date: Fri, 21 Sep 2018 11:17:15 -0700
Subject: ipv6: discard IP frag queue on more errors
Patch-mainline: v4.20-rc1
Git-commit: 2475f59c618ea58e9f72ae5ded2db392ee47810d
References: CVE-2018-5391 bsc#1103097

This is similar to how ipv4 now behaves:
commit 0ff89efb5246 ("ip: fail fast on IP defrag errors").

Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Michal Kubecek <mkubecek@suse.cz>

---
 net/ipv6/reassembly.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -144,7 +144,7 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 		 */
 		if (end < fq->q.len ||
 		    ((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len))
-			goto err;
+			goto discard_fq;
 		fq->q.flags |= INET_FRAG_LAST_IN;
 		fq->q.len = end;
 	} else {
@@ -161,20 +161,20 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 		if (end > fq->q.len) {
 			/* Some bits beyond end -> corruption. */
 			if (fq->q.flags & INET_FRAG_LAST_IN)
-				goto err;
+				goto discard_fq;
 			fq->q.len = end;
 		}
 	}
 
 	if (end == offset)
-		goto err;
+		goto discard_fq;
 
 	/* Point into the IP datagram 'data' part. */
 	if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
-		goto err;
+		goto discard_fq;
 
 	if (pskb_trim_rcsum(skb, end - offset))
-		goto err;
+		goto discard_fq;
 
 	/* Find out which fragments are in front and at the back of us
 	 * in the chain of fragments so far.  We must know where to put
@@ -423,6 +423,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 	rcu_read_lock();
 	__IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 	rcu_read_unlock();
+	inet_frag_kill(&fq->q);
 	return -1;
 }