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@xxxxxx>
Tested-by: Valdis Kletnieks <Valdis.Kletnieks@xxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
nf-next since the faulty commit is only present there.
net/ipv6/netfilter/nf_conntrack_reasm.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index 912bc3a..6e5f0e0d 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -441,11 +441,14 @@ 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);
--
2.4.10
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