From: Li RongQing <lirongqing@baidu.com>
Date: Tue, 26 Feb 2019 17:13:56 +0800
Subject: netfilter: nf_tables: check the result of dereferencing
base_chain->stats
Git-commit: a9f5e78c403d2d62ade4f4c85040efc85f4049b8
Patch-mainline: 5.1-rc1
References: git-fixes
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@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>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
net/netfilter/nf_tables_core.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -126,6 +126,7 @@ nft_do_chain(struct nft_pktinfo *pkt, vo
const struct nft_chain *chain = priv, *basechain = chain;
struct nft_base_chain *base_chain;
const struct net *net = nft_net(pkt);
+ struct nft_stats __percpu *pstats;
const struct nft_rule *rule;
const struct nft_expr *expr, *last;
struct nft_regs regs;
@@ -223,19 +224,18 @@ next_rule:
NFT_TRACETYPE_POLICY);
base_chain = nft_base_chain(basechain);
- if (!base_chain->stats)
- goto end;
rcu_read_lock_bh();
- stats = this_cpu_ptr(rcu_dereference(base_chain->stats));
- if (stats) {
+ pstats = READ_ONCE(base_chain->stats);
+ if (pstats) {
+ stats = this_cpu_ptr(pstats);
u64_stats_update_begin(&stats->syncp);
stats->pkts++;
stats->bytes += pkt->skb->len;
u64_stats_update_end(&stats->syncp);
}
rcu_read_unlock_bh();
-end:
+
return nft_base_chain(basechain)->policy;
}
EXPORT_SYMBOL_GPL(nft_do_chain);