Commit a9f5e78c authored Feb 26, 2019 by Li RongQing Committed by Pablo Neira Ayuso Mar 01, 2019

netfilter: nf_tables: check the result of dereferencing base_chain->stats



Check the result of dereferencing base_chain->stats, instead of result
of this_cpu_ptr with NULL.

base_chain->stats maybe be changed to NULL when a chain is updated and a
new NULL counter can be attached.

And we do not need to check returning of this_cpu_ptr since
base_chain->stats is from percpu allocator if it is non-NULL,
this_cpu_ptr returns a valid value.

And fix two sparse error by replacing rcu_access_pointer and
rcu_dereference with READ_ONCE under rcu_read_lock.

Thanks for Eric's help to finish this patch.

Fixes: 00924094 ("netfilter: nf_tables: don't assume chain stats are set when jumplabel is set")
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

parent cd642898

net/netfilter/nf_tables_core.c

+8 −6

Original line number	Diff line number	Diff line
		@@ -98,22 +98,24 @@ static noinline void nft_update_chain_stats(const struct nft_chain *chain,
		const struct nft_pktinfo *pkt)
		{
		struct nft_base_chain *base_chain;
		struct nft_stats __percpu *pstats;
		struct nft_stats *stats;

		base_chain = nft_base_chain(chain);
		if (!rcu_access_pointer(base_chain->stats))
		return;

		rcu_read_lock();
		pstats = READ_ONCE(base_chain->stats);
		if (pstats) {
		local_bh_disable();
		stats = this_cpu_ptr(rcu_dereference(base_chain->stats));
		if (stats) {
		stats = this_cpu_ptr(pstats);
		u64_stats_update_begin(&stats->syncp);
		stats->pkts++;
		stats->bytes += pkt->skb->len;
		u64_stats_update_end(&stats->syncp);
		}
		local_bh_enable();
		}
		rcu_read_unlock();
		}

		struct nft_jumpstack {
		const struct nft_chain *chain;

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