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netfilter: ipv6: nf_defrag: fix leakage of unqueued fragments

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With commit 997dd96471 ("net: IP6 defrag: use rbtrees in
nf_conntrack_reasm.c"), nf_ct_frag6_reasm() is now called from
nf_ct_frag6_queue(). With this change, nf_ct_frag6_queue() can fail
after the skb has been added to the fragment queue and
nf_ct_frag6_gather() was adapted to handle this case.

But nf_ct_frag6_queue() can still fail before the fragment has been
queued. nf_ct_frag6_gather() can't handle this case anymore, because it
has no way to know if nf_ct_frag6_queue() queued the fragment before
failing. If it didn't, the skb is lost as the error code is overwritten
with -EINPROGRESS.

Fix this by setting -EINPROGRESS directly in nf_ct_frag6_queue(), so
that nf_ct_frag6_gather() can propagate the error as is.

Fixes: 997dd96471 ("net: IP6 defrag: use rbtrees in nf_conntrack_reasm.c")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Guillaume Nault 2019-06-02 15:13:47 +02:00 committed by Pablo Neira Ayuso
parent 5142967ab5
commit a0d56cb911
1 changed files with 5 additions and 7 deletions
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12
net/ipv6/netfilter/nf_conntrack_reasm.c
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@ -293,7 +293,11 @@ static int nf_ct_frag6_queue(struct frag_queue *fq, struct sk_buff *skb,
skb->_skb_refdst = 0UL;
err = nf_ct_frag6_reasm(fq, skb, prev, dev);
skb->_skb_refdst = orefdst;
return err;
/* After queue has assumed skb ownership, only 0 or
* -EINPROGRESS must be returned.
*/
return err ? -EINPROGRESS : 0;
}
skb_dst_drop(skb);
@ -480,12 +484,6 @@ int nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 user)
ret = 0;
}
/* after queue has assumed skb ownership, only 0 or -EINPROGRESS
* must be returned.
*/
if (ret)
ret = -EINPROGRESS;
spin_unlock_bh(&fq->q.lock);
inet_frag_put(&fq->q);
return ret;