[ovs-dev] [PATCH 4/5] compat: nf_defrag_ipv6: fix NULL deref panic.

Joe Stringer joe at ovn.org
Thu Apr 21 21:07:27 UTC 2016


Upstream commit:
    netfilter: ipv6: nf_defrag: fix NULL deref panic

    Valdis reports NULL deref in nf_ct_frag6_gather.
    Problem is bogus use of skb_queue_walk() -- we miss first skb in the list
    since we start with head->next instead of head.

    In case the element we're looking for was head->next we won't find
    a result and then trip over NULL iter.

    (defrag uses plain NULL-terminated list rather than one terminated by
     head-of-list-pointer, which is what skb_queue_walk expects).

    Fixes: 029f7f3b8701cc7a ("netfilter: ipv6: nf_defrag: avoid/free clone operations")
    Reported-by: Valdis Kletnieks <Valdis.Kletnieks at vt.edu>
    Tested-by: Valdis Kletnieks <Valdis.Kletnieks at vt.edu>
    Signed-off-by: Florian Westphal <fw at strlen.de>
    Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>

Upstream: e97ac12859db ("netfilter: ipv6: nf_defrag: fix NULL deref panic")
Signed-off-by: Joe Stringer <joe at ovn.org>
---
 datapath/linux/compat/nf_conntrack_reasm.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/datapath/linux/compat/nf_conntrack_reasm.c b/datapath/linux/compat/nf_conntrack_reasm.c
index 31c47b487356..5000351e9664 100644
--- a/datapath/linux/compat/nf_conntrack_reasm.c
+++ b/datapath/linux/compat/nf_conntrack_reasm.c
@@ -365,11 +365,14 @@ nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *prev,  struct net_devic
 			return false;
 
 		fp->next = prev->next;
-		skb_queue_walk(head, iter) {
-			if (iter->next != prev)
-				continue;
-			iter->next = fp;
-			break;
+
+		iter = head;
+		while (iter) {
+			if (iter->next == prev) {
+				iter->next = fp;
+				break;
+			}
+			iter = iter->next;
 		}
 
 		skb_morph(prev, head);
-- 
2.1.4




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