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Message-ID: <20241017174109.85717-6-stefan.wiehler@nokia.com>
Date: Thu, 17 Oct 2024 19:37:47 +0200
From: Stefan Wiehler <stefan.wiehler@...ia.com>
To: "David S . Miller" <davem@...emloft.net>,
David Ahern <dsahern@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
Stefan Wiehler <stefan.wiehler@...ia.com>
Subject: [PATCH net v6 05/10] ip6mr: Lock RTNL before ip6mr_new_table() call in ip6mr_rules_init()
When IPV6_MROUTE_MULTIPLE_TABLES is enabled, multicast routing tables
must be read under RCU or RTNL lock. Since mr_table_alloc() can sleep,
we call ip6mr_new_table() under the RTNL lock.
Detected by Lockdep-RCU:
[ 10.247131] WARNING: suspicious RCU usage
[ 10.247133] 6.1.103-49518b10de-nokia_sm_x86 #1 Not tainted
[ 10.247135] -----------------------------
[ 10.247137] /net/ipv6/ip6mr.c:131 RCU-list traversed in non-reader section!!
[ 10.247140]
other info that might help us debug this:
[ 10.247142]
rcu_scheduler_active = 2, debug_locks = 1
[ 10.247144] 1 lock held by swapper/0/1:
[ 10.247147] #0: ffffffff82b374d0 (pernet_ops_rwsem){+.+.}-{3:3}, at: register_pernet_subsys+0x15/0x40
[ 10.247164]
stack backtrace:
[ 10.247166] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.1.103-49518b10de-nokia_sm_x86 #1
[ 10.247170] Hardware name: Nokia Asil/Default string, BIOS 0ACNA114 07/18/2024
[ 10.247175] Call Trace:
[ 10.247178] <TASK>
[ 10.247181] dump_stack_lvl+0xb7/0xe9
[ 10.247189] lockdep_rcu_suspicious.cold+0x2d/0x64
[ 10.247198] ip6mr_get_table+0x8a/0x90
[ 10.247203] ip6mr_net_init+0x7c/0x200
[ 10.247209] ops_init+0x37/0x1f0
[ 10.247215] register_pernet_operations+0x129/0x230
[ 10.247221] ? af_unix_init+0xca/0xca
[ 10.247227] register_pernet_subsys+0x24/0x40
[ 10.247231] ip6_mr_init+0x42/0xf2
[ 10.247235] inet6_init+0x133/0x3b9
[ 10.247238] do_one_initcall+0x74/0x290
[ 10.247247] kernel_init_freeable+0x251/0x294
[ 10.247253] ? rest_init+0x174/0x174
[ 10.247257] kernel_init+0x16/0x12c
[ 10.247260] ret_from_fork+0x1f/0x30
[ 10.247271] </TASK>
Signed-off-by: Stefan Wiehler <stefan.wiehler@...ia.com>
Fixes: d1db275dd3f6 ("ipv6: ip6mr: support multiple tables")
---
net/ipv6/ip6mr.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 017f9e31edfb..9bf42aafc7f0 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -236,11 +236,13 @@ static int __net_init ip6mr_rules_init(struct net *net)
INIT_LIST_HEAD(&net->ipv6.mr6_tables);
+ rtnl_lock();
mrt = ip6mr_new_table(net, RT6_TABLE_DFLT);
if (IS_ERR(mrt)) {
err = PTR_ERR(mrt);
goto err1;
}
+ rtnl_unlock();
err = fib_default_rule_add(ops, 0x7fff, RT6_TABLE_DFLT, 0);
if (err < 0)
@@ -254,6 +256,7 @@ static int __net_init ip6mr_rules_init(struct net *net)
ip6mr_free_table(mrt);
rtnl_unlock();
err1:
+ rtnl_unlock();
fib_rules_unregister(ops);
return err;
}
--
2.42.0
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