Commits
Eric Dumazet committed e37542ba111
netfilter: conntrack: avoid possible false sharing
As hinted by KCSAN, we need at least one READ_ONCE()
to prevent a compiler optimization.
More details on :
https://github.com/google/ktsan/wiki/READ_ONCE-and-WRITE_ONCE#it-may-improve-performance
sysbot report :
BUG: KCSAN: data-race in __nf_ct_refresh_acct / __nf_ct_refresh_acct
read to 0xffff888123eb4f08 of 4 bytes by interrupt on cpu 0:
__nf_ct_refresh_acct+0xd4/0x1b0 net/netfilter/nf_conntrack_core.c:1796
nf_ct_refresh_acct include/net/netfilter/nf_conntrack.h:201 [inline]
nf_conntrack_tcp_packet+0xd40/0x3390 net/netfilter/nf_conntrack_proto_tcp.c:1161
nf_conntrack_handle_packet net/netfilter/nf_conntrack_core.c:1633 [inline]
nf_conntrack_in+0x410/0xaa0 net/netfilter/nf_conntrack_core.c:1727
ipv4_conntrack_in+0x27/0x40 net/netfilter/nf_conntrack_proto.c:178
nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline]
nf_hook_slow+0x83/0x160 net/netfilter/core.c:512
nf_hook include/linux/netfilter.h:260 [inline]
NF_HOOK include/linux/netfilter.h:303 [inline]
ip_rcv+0x12f/0x1a0 net/ipv4/ip_input.c:523
__netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5004
__netif_receive_skb+0x37/0xf0 net/core/dev.c:5118
netif_receive_skb_internal+0x59/0x190 net/core/dev.c:5208
napi_skb_finish net/core/dev.c:5671 [inline]
napi_gro_receive+0x28f/0x330 net/core/dev.c:5704
receive_buf+0x284/0x30b0 drivers/net/virtio_net.c:1061
virtnet_receive drivers/net/virtio_net.c:1323 [inline]
virtnet_poll+0x436/0x7d0 drivers/net/virtio_net.c:1428
napi_poll net/core/dev.c:6352 [inline]
net_rx_action+0x3ae/0xa50 net/core/dev.c:6418
__do_softirq+0x115/0x33f kernel/softirq.c:292
write to 0xffff888123eb4f08 of 4 bytes by task 7191 on cpu 1:
__nf_ct_refresh_acct+0xfb/0x1b0 net/netfilter/nf_conntrack_core.c:1797
nf_ct_refresh_acct include/net/netfilter/nf_conntrack.h:201 [inline]
nf_conntrack_tcp_packet+0xd40/0x3390 net/netfilter/nf_conntrack_proto_tcp.c:1161
nf_conntrack_handle_packet net/netfilter/nf_conntrack_core.c:1633 [inline]
nf_conntrack_in+0x410/0xaa0 net/netfilter/nf_conntrack_core.c:1727
ipv4_conntrack_local+0xbe/0x130 net/netfilter/nf_conntrack_proto.c:200
nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline]
nf_hook_slow+0x83/0x160 net/netfilter/core.c:512
nf_hook include/linux/netfilter.h:260 [inline]
__ip_local_out+0x1f7/0x2b0 net/ipv4/ip_output.c:114
ip_local_out+0x31/0x90 net/ipv4/ip_output.c:123
__ip_queue_xmit+0x3a8/0xa40 net/ipv4/ip_output.c:532
ip_queue_xmit+0x45/0x60 include/net/ip.h:236
__tcp_transmit_skb+0xdeb/0x1cd0 net/ipv4/tcp_output.c:1158
__tcp_send_ack+0x246/0x300 net/ipv4/tcp_output.c:3685
tcp_send_ack+0x34/0x40 net/ipv4/tcp_output.c:3691
tcp_cleanup_rbuf+0x130/0x360 net/ipv4/tcp.c:1575
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7191 Comm: syz-fuzzer Not tainted 5.3.0+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Fixes: cc16921351d8 ("netfilter: conntrack: avoid same-timeout update")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Jozsef Kadlecsik <kadlec@netfilter.org>
Cc: Florian Westphal <fw@strlen.de>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>