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: 009240940e84c1 ("netfilter: nf_tables: don't assume chain stats are set when jumplabel is set")
Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: Zhang Yu <zhangyu31@xxxxxxxxx>
Signed-off-by: Li RongQing <lirongqing@xxxxxxxxx>
---
v1 -->v2: move the dereferencing under bh disable context, and fix two sparse
net/netfilter/nf_tables_core.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
index 2a00aef7b6d4..7dfbc6746846 100644
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -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 {
--
2.16.2
