From: Qian Cai <cai@lca.pw>
To: pablo@netfilter.org, kadlec@netfilter.org, fw@strlen.de
Cc: davem@davemloft.net, netfilter-devel@vger.kernel.org,
coreteam@netfilter.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, Qian Cai <cai@lca.pw>
Subject: [PATCH] netfilter/nf_tables: silence a RCU-list warning
Date: Wed, 25 Mar 2020 10:31:42 -0400 [thread overview]
Message-ID: <20200325143142.6955-1-cai@lca.pw> (raw)
It is safe to traverse &net->nft.tables with &net->nft.commit_mutex
held using list_for_each_entry_rcu(). Silence the PROVE_RCU_LIST false
positive,
WARNING: suspicious RCU usage
net/netfilter/nf_tables_api.c:523 RCU-list traversed in non-reader section!!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by iptables/1384:
#0: ffffffff9745c4a8 (&net->nft.commit_mutex){+.+.}, at: nf_tables_valid_genid+0x25/0x60 [nf_tables]
Call Trace:
dump_stack+0xa1/0xea
lockdep_rcu_suspicious+0x103/0x10d
nft_table_lookup.part.0+0x116/0x120 [nf_tables]
nf_tables_newtable+0x12c/0x7d0 [nf_tables]
nfnetlink_rcv_batch+0x559/0x1190 [nfnetlink]
nfnetlink_rcv+0x1da/0x210 [nfnetlink]
netlink_unicast+0x306/0x460
netlink_sendmsg+0x44b/0x770
____sys_sendmsg+0x46b/0x4a0
___sys_sendmsg+0x138/0x1a0
__sys_sendmsg+0xb6/0x130
__x64_sys_sendmsg+0x48/0x50
do_syscall_64+0x69/0xf4
entry_SYSCALL_64_after_hwframe+0x49/0xb3
Signed-off-by: Qian Cai <cai@lca.pw>
---
net/netfilter/nf_tables_api.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 38c680f28f15..e398d1491057 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -520,7 +520,8 @@ static struct nft_table *nft_table_lookup(const struct net *net,
if (nla == NULL)
return ERR_PTR(-EINVAL);
- list_for_each_entry_rcu(table, &net->nft.tables, list) {
+ list_for_each_entry_rcu(table, &net->nft.tables, list,
+ lockdep_is_held(&net->nft.commit_mutex)) {
if (!nla_strcmp(nla, table->name) &&
table->family == family &&
nft_active_genmask(table, genmask))
--
2.21.0 (Apple Git-122.2)
next reply other threads:[~2020-03-25 14:32 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 14:31 Qian Cai [this message]
2020-03-25 23:13 ` [PATCH] netfilter/nf_tables: silence a RCU-list warning Florian Westphal
2020-03-26 13:46 ` Pablo Neira Ayuso
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