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Message-Id: <20191026131600.2507-49-sashal@kernel.org>
Date: Sat, 26 Oct 2019 09:15:10 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: Eric Dumazet <edumazet@...gle.com>,
syzbot <syzkaller@...glegroups.com>,
Jozsef Kadlecsik <kadlec@...filter.org>,
Florian Westphal <fw@...len.de>,
Pablo Neira Ayuso <pablo@...filter.org>,
Jakub Kicinski <jakub.kicinski@...ronome.com>,
Sasha Levin <sashal@...nel.org>,
netfilter-devel@...r.kernel.org, coreteam@...filter.org,
netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 5.3 49/99] netfilter: conntrack: avoid possible false sharing
From: Eric Dumazet <edumazet@...gle.com>
[ Upstream commit e37542ba111f3974dc622ae0a21c1787318de500 ]
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@...gle.com>
Reported-by: syzbot <syzkaller@...glegroups.com>
Cc: Jozsef Kadlecsik <kadlec@...filter.org>
Cc: Florian Westphal <fw@...len.de>
Acked-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
net/netfilter/nf_conntrack_core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 81a8ef42b88d3..56b1cf82ed3aa 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1793,8 +1793,8 @@ void __nf_ct_refresh_acct(struct nf_conn *ct,
if (nf_ct_is_confirmed(ct))
extra_jiffies += nfct_time_stamp;
- if (ct->timeout != extra_jiffies)
- ct->timeout = extra_jiffies;
+ if (READ_ONCE(ct->timeout) != extra_jiffies)
+ WRITE_ONCE(ct->timeout, extra_jiffies);
acct:
if (do_acct)
nf_ct_acct_update(ct, ctinfo, skb->len);
--
2.20.1
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