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Subject[PATCH 4.19 42/79] net: annotate lockless accesses to sk->sk_napi_id
Date
From: Eric Dumazet <edumazet@google.com>

[ Upstream commit ee8d153d46a3b98c064ee15c0c0a3bbf1450e5a1 ]

We already annotated most accesses to sk->sk_napi_id

We missed sk_mark_napi_id() and sk_mark_napi_id_once()
which might be called without socket lock held in UDP stack.

KCSAN reported :
BUG: KCSAN: data-race in udpv6_queue_rcv_one_skb / udpv6_queue_rcv_one_skb

write to 0xffff888121c6d108 of 4 bytes by interrupt on cpu 0:
sk_mark_napi_id include/net/busy_poll.h:125 [inline]
__udpv6_queue_rcv_skb net/ipv6/udp.c:571 [inline]
udpv6_queue_rcv_one_skb+0x70c/0xb40 net/ipv6/udp.c:672
udpv6_queue_rcv_skb+0xb5/0x400 net/ipv6/udp.c:689
udp6_unicast_rcv_skb.isra.0+0xd7/0x180 net/ipv6/udp.c:832
__udp6_lib_rcv+0x69c/0x1770 net/ipv6/udp.c:913
udpv6_rcv+0x2b/0x40 net/ipv6/udp.c:1015
ip6_protocol_deliver_rcu+0x22a/0xbe0 net/ipv6/ip6_input.c:409
ip6_input_finish+0x30/0x50 net/ipv6/ip6_input.c:450
NF_HOOK include/linux/netfilter.h:305 [inline]
NF_HOOK include/linux/netfilter.h:299 [inline]
ip6_input+0x177/0x190 net/ipv6/ip6_input.c:459
dst_input include/net/dst.h:442 [inline]
ip6_rcv_finish+0x110/0x140 net/ipv6/ip6_input.c:76
NF_HOOK include/linux/netfilter.h:305 [inline]
NF_HOOK include/linux/netfilter.h:299 [inline]
ipv6_rcv+0x1a1/0x1b0 net/ipv6/ip6_input.c:284
__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

write to 0xffff888121c6d108 of 4 bytes by interrupt on cpu 1:
sk_mark_napi_id include/net/busy_poll.h:125 [inline]
__udpv6_queue_rcv_skb net/ipv6/udp.c:571 [inline]
udpv6_queue_rcv_one_skb+0x70c/0xb40 net/ipv6/udp.c:672
udpv6_queue_rcv_skb+0xb5/0x400 net/ipv6/udp.c:689
udp6_unicast_rcv_skb.isra.0+0xd7/0x180 net/ipv6/udp.c:832
__udp6_lib_rcv+0x69c/0x1770 net/ipv6/udp.c:913
udpv6_rcv+0x2b/0x40 net/ipv6/udp.c:1015
ip6_protocol_deliver_rcu+0x22a/0xbe0 net/ipv6/ip6_input.c:409
ip6_input_finish+0x30/0x50 net/ipv6/ip6_input.c:450
NF_HOOK include/linux/netfilter.h:305 [inline]
NF_HOOK include/linux/netfilter.h:299 [inline]
ip6_input+0x177/0x190 net/ipv6/ip6_input.c:459
dst_input include/net/dst.h:442 [inline]
ip6_rcv_finish+0x110/0x140 net/ipv6/ip6_input.c:76
NF_HOOK include/linux/netfilter.h:305 [inline]
NF_HOOK include/linux/netfilter.h:299 [inline]
ipv6_rcv+0x1a1/0x1b0 net/ipv6/ip6_input.c:284
__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

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10890 Comm: syz-executor.0 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Fixes: e68b6e50fa35 ("udp: enable busy polling for all sockets")
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/busy_poll.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/include/net/busy_poll.h
+++ b/include/net/busy_poll.h
@@ -134,7 +134,7 @@ static inline void skb_mark_napi_id(stru
static inline void sk_mark_napi_id(struct sock *sk, const struct sk_buff *skb)
{
#ifdef CONFIG_NET_RX_BUSY_POLL
- sk->sk_napi_id = skb->napi_id;
+ WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
#endif
sk_rx_queue_set(sk, skb);
}
@@ -144,8 +144,8 @@ static inline void sk_mark_napi_id_once(
const struct sk_buff *skb)
{
#ifdef CONFIG_NET_RX_BUSY_POLL
- if (!sk->sk_napi_id)
- sk->sk_napi_id = skb->napi_id;
+ if (!READ_ONCE(sk->sk_napi_id))
+ WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
#endif
}


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