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Eric Dumazet b01e1c0307 ipv6: fix possible race in __fib6_drop_pcpu_from() 
syzbot found a race in __fib6_drop_pcpu_from() [1]

If compiler reads more than once (*ppcpu_rt),
second read could read NULL, if another cpu clears
the value in rt6_get_pcpu_route().

Add a READ_ONCE() to prevent this race.

Also add rcu_read_lock()/rcu_read_unlock() because
we rely on RCU protection while dereferencing pcpu_rt.

[1]

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000012: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097]
CPU: 0 PID: 7543 Comm: kworker/u8:17 Not tainted 6.10.0-rc1-syzkaller-00013-g2bfcfd584ff5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Workqueue: netns cleanup_net
 RIP: 0010:__fib6_drop_pcpu_from.part.0+0x10a/0x370 net/ipv6/ip6_fib.c:984
Code: f8 48 c1 e8 03 80 3c 28 00 0f 85 16 02 00 00 4d 8b 3f 4d 85 ff 74 31 e8 74 a7 fa f7 49 8d bf 90 00 00 00 48 89 f8 48 c1 e8 03 <80> 3c 28 00 0f 85 1e 02 00 00 49 8b 87 90 00 00 00 48 8b 0c 24 48
RSP: 0018:ffffc900040df070 EFLAGS: 00010206
RAX: 0000000000000012 RBX: 0000000000000001 RCX: ffffffff89932e16
RDX: ffff888049dd1e00 RSI: ffffffff89932d7c RDI: 0000000000000091
RBP: dffffc0000000000 R08: 0000000000000005 R09: 0000000000000007
R10: 0000000000000001 R11: 0000000000000006 R12: ffff88807fa080b8
R13: fffffbfff1a9a07d R14: ffffed100ff41022 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b9200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32c26000 CR3: 000000005d56e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
  __fib6_drop_pcpu_from net/ipv6/ip6_fib.c:966 [inline]
  fib6_drop_pcpu_from net/ipv6/ip6_fib.c:1027 [inline]
  fib6_purge_rt+0x7f2/0x9f0 net/ipv6/ip6_fib.c:1038
  fib6_del_route net/ipv6/ip6_fib.c:1998 [inline]
  fib6_del+0xa70/0x17b0 net/ipv6/ip6_fib.c:2043
  fib6_clean_node+0x426/0x5b0 net/ipv6/ip6_fib.c:2205
  fib6_walk_continue+0x44f/0x8d0 net/ipv6/ip6_fib.c:2127
  fib6_walk+0x182/0x370 net/ipv6/ip6_fib.c:2175
  fib6_clean_tree+0xd7/0x120 net/ipv6/ip6_fib.c:2255
  __fib6_clean_all+0x100/0x2d0 net/ipv6/ip6_fib.c:2271
  rt6_sync_down_dev net/ipv6/route.c:4906 [inline]
  rt6_disable_ip+0x7ed/0xa00 net/ipv6/route.c:4911
  addrconf_ifdown.isra.0+0x117/0x1b40 net/ipv6/addrconf.c:3855
  addrconf_notify+0x223/0x19e0 net/ipv6/addrconf.c:3778
  notifier_call_chain+0xb9/0x410 kernel/notifier.c:93
  call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:1992
  call_netdevice_notifiers_extack net/core/dev.c:2030 [inline]
  call_netdevice_notifiers net/core/dev.c:2044 [inline]
  dev_close_many+0x333/0x6a0 net/core/dev.c:1585
  unregister_netdevice_many_notify+0x46d/0x19f0 net/core/dev.c:11193
  unregister_netdevice_many net/core/dev.c:11276 [inline]
  default_device_exit_batch+0x85b/0xae0 net/core/dev.c:11759
  ops_exit_list+0x128/0x180 net/core/net_namespace.c:178
  cleanup_net+0x5b7/0xbf0 net/core/net_namespace.c:640
  process_one_work+0x9fb/0x1b60 kernel/workqueue.c:3231
  process_scheduled_works kernel/workqueue.c:3312 [inline]
  worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393
  kthread+0x2c1/0x3a0 kernel/kthread.c:389
  ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Fixes: d52d3997f8 ("ipv6: Create percpu rt6_info")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20240604193549.981839-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
 		2024-06-06 13:05:54 +02:00
..
ila ila: block BH in ila_output() 2024-06-03 18:50:09 -07:00
netfilter netfilter: use NF_DROP instead of -NF_DROP 2024-05-06 16:29:21 +02:00
Kconfig
…
Makefile
…
addrconf.c net: ipv{6,4}: Remove the now superfluous sentinel elements from ctl_table array 2024-05-03 13:29:42 +01:00
addrconf_core.c
…
addrlabel.c ipv6: remove RTNL protection from ip6addrlbl_dump() 2024-04-08 11:01:05 +01:00
af_inet6.c
…
ah6.c
…
anycast.c ipv6: anycast: use call_rcu_hurry() in aca_put() 2024-05-01 11:46:21 +01:00
calipso.c
…
datagram.c
…
esp6.c ipsec-next-2024-05-03 2024-05-06 19:14:56 -07:00
esp6_offload.c
…
exthdrs.c
…
exthdrs_core.c
…
exthdrs_offload.c
…
fib6_notifier.c
…
fib6_rules.c ipv6: fib6_rules: avoid possible NULL dereference in fib6_rule_action() 2024-05-08 18:50:53 -07:00
fou6.c
…
icmp.c net: ipv{6,4}: Remove the now superfluous sentinel elements from ctl_table array 2024-05-03 13:29:42 +01:00
inet6_connection_sock.c
…
inet6_hashtables.c tcp: get rid of twsk_unique() 2024-05-09 20:25:55 -07:00
ioam6.c
…
ioam6_iptunnel.c ipv6: ioam: block BH from ioam6_output() 2024-06-03 18:50:08 -07:00
ip6_checksum.c
…
ip6_fib.c ipv6: fix possible race in __fib6_drop_pcpu_from() 2024-06-06 13:05:54 +02:00
ip6_flowlabel.c
…
ip6_gre.c net: ip6_gre: Remove generic .ndo_get_stats64 2024-04-15 11:32:13 +01:00
ip6_icmp.c
…
ip6_input.c
…
ip6_offload.c net: gro: initialize network_offset in network layer 2024-05-27 16:46:59 -07:00
ip6_offload.h
…
ip6_output.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2024-05-09 10:01:01 -07:00
ip6_tunnel.c net: annotate writes on dev->mtu from ndo_change_mtu() 2024-05-07 16:19:14 -07:00
ip6_udp_tunnel.c
…
ip6_vti.c net: annotate writes on dev->mtu from ndo_change_mtu() 2024-05-07 16:19:14 -07:00
ip6mr.c ipv6: introduce dst_rt6_info() helper 2024-04-29 13:32:01 +01:00
ipcomp6.c
…
ipv6_sockglue.c
…
mcast.c
…
mcast_snoop.c
…
mip6.c
…
ndisc.c ipv6: introduce dst_rt6_info() helper 2024-04-29 13:32:01 +01:00
netfilter.c
…
output_core.c
…
ping.c ipv6: introduce dst_rt6_info() helper 2024-04-29 13:32:01 +01:00
proc.c
…
protocol.c
…
raw.c ipv6: introduce dst_rt6_info() helper 2024-04-29 13:32:01 +01:00
reassembly.c net: ipv6: fix wrong start position when receive hop-by-hop fragment 2024-05-10 10:04:06 +01:00
route.c ipv6: fix possible race in __fib6_drop_pcpu_from() 2024-06-06 13:05:54 +02:00
rpl.c
…
rpl_iptunnel.c net: ipv6: rpl_iptunnel: block BH in rpl_output() and rpl_input() 2024-06-03 18:50:08 -07:00
seg6.c ipv6: sr: fix invalid unregister error path 2024-05-10 19:27:46 -07:00
seg6_hmac.c ipv6: sr: fix memleak in seg6_hmac_init_algo 2024-05-21 13:16:25 +02:00
seg6_iptunnel.c ipv6: sr: block BH in seg6_output_core() and seg6_input_core() 2024-06-03 18:50:08 -07:00
seg6_local.c
…
sit.c
…
syncookies.c
…
sysctl_net_ipv6.c net: ipv{6,4}: Remove the now superfluous sentinel elements from ctl_table array 2024-05-03 13:29:42 +01:00
tcp_ao.c
…
tcp_ipv6.c tcp: reduce accepted window in NEW_SYN_RECV state 2024-05-27 16:47:23 -07:00
tcpv6_offload.c net: gro: use cb instead of skb->network_header 2024-05-13 14:44:06 -07:00
tunnel6.c
…
udp.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2024-05-02 12:06:25 -07:00
udp_impl.h
…
udp_offload.c net: gro: fix udp bad offset in socket lookup by adding {inner_}network_offset to napi_gro_cb 2024-05-02 11:02:48 +02:00
udplite.c
…
xfrm6_input.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2024-05-09 10:01:01 -07:00
xfrm6_output.c
…
xfrm6_policy.c net: ipv{6,4}: Remove the now superfluous sentinel elements from ctl_table array 2024-05-03 13:29:42 +01:00
xfrm6_protocol.c
…
xfrm6_state.c
…
xfrm6_tunnel.c
…