Thread (10 messages) flat view 10 messages, 5 authors, 2018-10-25

Re: crash in xt_policy due to skb_dst_drop() in nf_ct_frag6_gather()

From: Florian Westphal <fw@strlen.de>
Date: 2018-10-16 16:00:35 

Maciej Żenczykowski [off-list ref] wrote:

I am currently travelling and not able to investigate
until next week.
quoted hunk ↗ jump to hunk
commit ad8b1ffc3efae2f65080bdb11145c87d299b8f9a
Author: Florian Westphal [off-list ref]
    netfilter: ipv6: nf_defrag: drop skb dst before queueing

+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -618,6 +618,8 @@ int nf_ct_frag6_gather(struct net *net, struct
sk_buff *skb, u32 user)
            fq->q.meat == fq->q.len &&
            nf_ct_frag6_reasm(fq, skb, dev))
                ret = 0;
+       else
+               skb_dst_drop(skb);
This is only supposed to drop dst of skbs that are enqueued,
i.e. frag6_gather returns NF_STOLEN.

In case skb completes the queue, then that skbs dst_entry
is supposed to be kept, so skb_dst() does NOT return NULL.

Its not supposed to be any different than ipv4 defrag.

const struct dst_entry *dst = skb_dst(skb); // returns NULL
That is not supposed to happen.
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help