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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: 009240940e ("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>
hifive-unleashed-5.1
Li RongQing 2019-02-26 17:13:56 +08:00 committed by Pablo Neira Ayuso
parent cd6428988b
commit a9f5e78c40
1 changed files with 8 additions and 6 deletions
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14
net/netfilter/nf_tables_core.c
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@ -98,21 +98,23 @@ 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;
local_bh_disable();
stats = this_cpu_ptr(rcu_dereference(base_chain->stats));
if (stats) {
rcu_read_lock();
pstats = READ_ONCE(base_chain->stats);
if (pstats) {
local_bh_disable();
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();
}
local_bh_enable();
rcu_read_unlock();
}
struct nft_jumpstack {