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4b4b84468a
struct ip6_sf_socklist and ipv6_mc_socklist are per-socket MLD data.
These data are protected by rtnl lock, socket lock, and RCU.
So, when these are used, it verifies whether rtnl lock is acquired or not.
ip6_mc_msfget() is called by do_ipv6_getsockopt().
But caller doesn't acquire rtnl lock.
So, when these data are used in the ip6_mc_msfget() lockdep warns about it.
But accessing these is actually safe because socket lock was acquired by
do_ipv6_getsockopt().
So, it changes lockdep annotation from rtnl lock to socket lock.
(rtnl_dereference -> sock_dereference)
Locking graph for mld data is like below:
When writing mld data:
do_ipv6_setsockopt()
rtnl_lock
lock_sock
(mld functions)
idev->mc_lock(if per-interface mld data is modified)
When reading mld data:
do_ipv6_getsockopt()
lock_sock
ip6_mc_msfget()
Splat looks like:
=============================
WARNING: suspicious RCU usage
5.12.0-rc4+ #503 Not tainted
-----------------------------
net/ipv6/mcast.c:610 suspicious rcu_dereference_protected() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by mcast-listener-/923:
#0: ffff888007958a70 (sk_lock-AF_INET6){+.+.}-{0:0}, at:
ipv6_get_msfilter+0xaf/0x190
stack backtrace:
CPU: 1 PID: 923 Comm: mcast-listener- Not tainted 5.12.0-rc4+ #503
Call Trace:
dump_stack+0xa4/0xe5
ip6_mc_msfget+0x553/0x6c0
? ipv6_sock_mc_join_ssm+0x10/0x10
? lockdep_hardirqs_on_prepare+0x3e0/0x3e0
? mark_held_locks+0xb7/0x120
? lockdep_hardirqs_on_prepare+0x27c/0x3e0
? __local_bh_enable_ip+0xa5/0xf0
? lock_sock_nested+0x82/0xf0
ipv6_get_msfilter+0xc3/0x190
? compat_ipv6_get_msfilter+0x300/0x300
? lock_downgrade+0x690/0x690
do_ipv6_getsockopt.isra.6.constprop.13+0x1809/0x29e0
? do_ipv6_mcast_group_source+0x150/0x150
? register_lock_class+0x1750/0x1750
? kvm_sched_clock_read+0x14/0x30
? sched_clock+0x5/0x10
? sched_clock_cpu+0x18/0x170
? find_held_lock+0x3a/0x1c0
? lock_downgrade+0x690/0x690
? ipv6_getsockopt+0xdb/0x1b0
ipv6_getsockopt+0xdb/0x1b0
[ ... ]
Fixes:
|
||
|---|---|---|
| .. | ||
| ila | ||
| netfilter | ||
| addrconf_core.c | ||
| addrconf.c | ||
| addrlabel.c | ||
| af_inet6.c | ||
| ah6.c | ||
| anycast.c | ||
| calipso.c | ||
| datagram.c | ||
| esp6_offload.c | ||
| esp6.c | ||
| exthdrs_core.c | ||
| exthdrs_offload.c | ||
| exthdrs.c | ||
| fib6_notifier.c | ||
| fib6_rules.c | ||
| fou6.c | ||
| icmp.c | ||
| inet6_connection_sock.c | ||
| inet6_hashtables.c | ||
| ip6_checksum.c | ||
| ip6_fib.c | ||
| ip6_flowlabel.c | ||
| ip6_gre.c | ||
| ip6_icmp.c | ||
| ip6_input.c | ||
| ip6_offload.c | ||
| ip6_offload.h | ||
| ip6_output.c | ||
| ip6_tunnel.c | ||
| ip6_udp_tunnel.c | ||
| ip6_vti.c | ||
| ip6mr.c | ||
| ipcomp6.c | ||
| ipv6_sockglue.c | ||
| Kconfig | ||
| Makefile | ||
| mcast_snoop.c | ||
| mcast.c | ||
| mip6.c | ||
| ndisc.c | ||
| netfilter.c | ||
| output_core.c | ||
| ping.c | ||
| proc.c | ||
| protocol.c | ||
| raw.c | ||
| reassembly.c | ||
| route.c | ||
| rpl_iptunnel.c | ||
| rpl.c | ||
| seg6_hmac.c | ||
| seg6_iptunnel.c | ||
| seg6_local.c | ||
| seg6.c | ||
| sit.c | ||
| syncookies.c | ||
| sysctl_net_ipv6.c | ||
| tcp_ipv6.c | ||
| tcpv6_offload.c | ||
| tunnel6.c | ||
| udp_impl.h | ||
| udp_offload.c | ||
| udp.c | ||
| udplite.c | ||
| xfrm6_input.c | ||
| xfrm6_output.c | ||
| xfrm6_policy.c | ||
| xfrm6_protocol.c | ||
| xfrm6_state.c | ||
| xfrm6_tunnel.c | ||