netfilter: nf_tables: avoid skb access on nf_stolen
When verdict is NF_STOLEN, the skb might have been freed. When tracing is enabled, this can result in a use-after-free: 1. access to skb->nf_trace 2. access to skb->mark 3. computation of trace id 4. dump of packet payload To avoid 1, keep a cached copy of skb->nf_trace in the trace state struct. Refresh this copy whenever verdict is != STOLEN. Avoid 2 by skipping skb->mark access if verdict is STOLEN. 3 is avoided by precomputing the trace id. Only dump the packet when verdict is not "STOLEN". Reported-by:Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by:
Florian Westphal <fw@strlen.de> Signed-off-by:
Pablo Neira Ayuso <pablo@netfilter.org>
parent
05907f10
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