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Subject[PATCH 4.19 41/79] net: annotate accesses to sk->sk_incoming_cpu
Date
From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 7170a977743b72cf3eb46ef6ef89885dc7ad3621 ]

This socket field can be read and written by concurrent cpus.

Use READ_ONCE() and WRITE_ONCE() annotations to document this,
and avoid some compiler 'optimizations'.

KCSAN reported :

BUG: KCSAN: data-race in tcp_v4_rcv / tcp_v4_rcv

write to 0xffff88812220763c of 4 bytes by interrupt on cpu 0:
sk_incoming_cpu_update include/net/sock.h:953 [inline]
tcp_v4_rcv+0x1b3c/0x1bb0 net/ipv4/tcp_ipv4.c:1934
ip_protocol_deliver_rcu+0x4d/0x420 net/ipv4/ip_input.c:204
ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231
NF_HOOK include/linux/netfilter.h:305 [inline]
NF_HOOK include/linux/netfilter.h:299 [inline]
ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252
dst_input include/net/dst.h:442 [inline]
ip_rcv_finish+0x121/0x160 net/ipv4/ip_input.c:413
NF_HOOK include/linux/netfilter.h:305 [inline]
NF_HOOK include/linux/netfilter.h:299 [inline]
ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:523
__netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5010
__netif_receive_skb+0x37/0xf0 net/core/dev.c:5124
process_backlog+0x1d3/0x420 net/core/dev.c:5955
napi_poll net/core/dev.c:6392 [inline]
net_rx_action+0x3ae/0xa90 net/core/dev.c:6460
__do_softirq+0x115/0x33f kernel/softirq.c:292
do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1082
do_softirq.part.0+0x6b/0x80 kernel/softirq.c:337
do_softirq kernel/softirq.c:329 [inline]
__local_bh_enable_ip+0x76/0x80 kernel/softirq.c:189

read to 0xffff88812220763c of 4 bytes by interrupt on cpu 1:
sk_incoming_cpu_update include/net/sock.h:952 [inline]
tcp_v4_rcv+0x181a/0x1bb0 net/ipv4/tcp_ipv4.c:1934
ip_protocol_deliver_rcu+0x4d/0x420 net/ipv4/ip_input.c:204
ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231
NF_HOOK include/linux/netfilter.h:305 [inline]
NF_HOOK include/linux/netfilter.h:299 [inline]
ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252
dst_input include/net/dst.h:442 [inline]
ip_rcv_finish+0x121/0x160 net/ipv4/ip_input.c:413
NF_HOOK include/linux/netfilter.h:305 [inline]
NF_HOOK include/linux/netfilter.h:299 [inline]
ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:523
__netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5010
__netif_receive_skb+0x37/0xf0 net/core/dev.c:5124
process_backlog+0x1d3/0x420 net/core/dev.c:5955
napi_poll net/core/dev.c:6392 [inline]
net_rx_action+0x3ae/0xa90 net/core/dev.c:6460
__do_softirq+0x115/0x33f kernel/softirq.c:292
run_ksoftirqd+0x46/0x60 kernel/softirq.c:603
smpboot_thread_fn+0x37d/0x4a0 kernel/smpboot.c:165

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16 Comm: ksoftirqd/1 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/net/sock.h | 4 ++--
net/core/sock.c | 4 ++--
net/ipv4/inet_hashtables.c | 2 +-
net/ipv4/udp.c | 2 +-
net/ipv6/inet6_hashtables.c | 2 +-
net/ipv6/udp.c | 2 +-
6 files changed, 8 insertions(+), 8 deletions(-)

--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -945,8 +945,8 @@ static inline void sk_incoming_cpu_updat
{
int cpu = raw_smp_processor_id();

- if (unlikely(sk->sk_incoming_cpu != cpu))
- sk->sk_incoming_cpu = cpu;
+ if (unlikely(READ_ONCE(sk->sk_incoming_cpu) != cpu))
+ WRITE_ONCE(sk->sk_incoming_cpu, cpu);
}

static inline void sock_rps_record_flow_hash(__u32 hash)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1005,7 +1005,7 @@ set_rcvbuf:
break;

case SO_INCOMING_CPU:
- sk->sk_incoming_cpu = val;
+ WRITE_ONCE(sk->sk_incoming_cpu, val);
break;

case SO_CNX_ADVICE:
@@ -1341,7 +1341,7 @@ int sock_getsockopt(struct socket *sock,
break;

case SO_INCOMING_CPU:
- v.val = sk->sk_incoming_cpu;
+ v.val = READ_ONCE(sk->sk_incoming_cpu);
break;

case SO_MEMINFO:
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -248,7 +248,7 @@ static inline int compute_score(struct s
if (sk->sk_bound_dev_if)
score += 4;
}
- if (sk->sk_incoming_cpu == raw_smp_processor_id())
+ if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
score++;
}
return score;
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -408,7 +408,7 @@ static int compute_score(struct sock *sk
score += 4;
}

- if (sk->sk_incoming_cpu == raw_smp_processor_id())
+ if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
score++;
return score;
}
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -118,7 +118,7 @@ static inline int compute_score(struct s
if (sk->sk_bound_dev_if)
score++;
}
- if (sk->sk_incoming_cpu == raw_smp_processor_id())
+ if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
score++;
}
return score;
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -154,7 +154,7 @@ static int compute_score(struct sock *sk
score++;
}

- if (sk->sk_incoming_cpu == raw_smp_processor_id())
+ if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
score++;

return score;

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