From 1f142c17d19a5618d5a633195a46f2c8be9bf232 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 9 Oct 2019 15:10:15 -0700 Subject: tcp: annotate lockless access to tcp_memory_pressure tcp_memory_pressure is read without holding any lock, and its value could be changed on other cpus. Use READ_ONCE() to annotate these lockless reads. The write side is already using atomic ops. Fixes: b8da51ebb1aa ("tcp: introduce tcp_under_memory_pressure()") Signed-off-by: Eric Dumazet Signed-off-by: Jakub Kicinski --- include/net/tcp.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/net/tcp.h') diff --git a/include/net/tcp.h b/include/net/tcp.h index c9a3f9688223..88e63d64c698 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -258,7 +258,7 @@ static inline bool tcp_under_memory_pressure(const struct sock *sk) mem_cgroup_under_socket_pressure(sk->sk_memcg)) return true; - return tcp_memory_pressure; + return READ_ONCE(tcp_memory_pressure); } /* * The next routines deal with comparing 32 bit unsigned ints -- cgit v1.2.3 From 70c2655849a25431f31b505a07fe0c861e5e41fb Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 9 Oct 2019 15:41:03 -0700 Subject: net: silence KCSAN warnings about sk->sk_backlog.len reads sk->sk_backlog.len can be written by BH handlers, and read from process contexts in a lockless way. Note the write side should also use WRITE_ONCE() or a variant. We need some agreement about the best way to do this. syzbot reported : BUG: KCSAN: data-race in tcp_add_backlog / tcp_grow_window.isra.0 write to 0xffff88812665f32c of 4 bytes by interrupt on cpu 1: sk_add_backlog include/net/sock.h:934 [inline] tcp_add_backlog+0x4a0/0xcc0 net/ipv4/tcp_ipv4.c:1737 tcp_v4_rcv+0x1aba/0x1bf0 net/ipv4/tcp_ipv4.c:1925 ip_protocol_deliver_rcu+0x51/0x470 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: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 read to 0xffff88812665f32c of 4 bytes by task 7292 on cpu 0: tcp_space include/net/tcp.h:1373 [inline] tcp_grow_window.isra.0+0x6b/0x480 net/ipv4/tcp_input.c:413 tcp_event_data_recv+0x68f/0x990 net/ipv4/tcp_input.c:717 tcp_rcv_established+0xbfe/0xf50 net/ipv4/tcp_input.c:5618 tcp_v4_do_rcv+0x381/0x4e0 net/ipv4/tcp_ipv4.c:1542 sk_backlog_rcv include/net/sock.h:945 [inline] __release_sock+0x135/0x1e0 net/core/sock.c:2427 release_sock+0x61/0x160 net/core/sock.c:2943 tcp_recvmsg+0x63b/0x1a30 net/ipv4/tcp.c:2181 inet_recvmsg+0xbb/0x250 net/ipv4/af_inet.c:838 sock_recvmsg_nosec net/socket.c:871 [inline] sock_recvmsg net/socket.c:889 [inline] sock_recvmsg+0x92/0xb0 net/socket.c:885 sock_read_iter+0x15f/0x1e0 net/socket.c:967 call_read_iter include/linux/fs.h:1864 [inline] new_sync_read+0x389/0x4f0 fs/read_write.c:414 __vfs_read+0xb1/0xc0 fs/read_write.c:427 vfs_read fs/read_write.c:461 [inline] vfs_read+0x143/0x2c0 fs/read_write.c:446 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 7292 Comm: syz-fuzzer Not tainted 5.3.0+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: Jakub Kicinski --- include/net/tcp.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/net/tcp.h') diff --git a/include/net/tcp.h b/include/net/tcp.h index 88e63d64c698..35f6f7e0fdc2 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1380,7 +1380,8 @@ static inline int tcp_win_from_space(const struct sock *sk, int space) /* Note: caller must be prepared to deal with negative returns */ static inline int tcp_space(const struct sock *sk) { - return tcp_win_from_space(sk, sk->sk_rcvbuf - sk->sk_backlog.len - + return tcp_win_from_space(sk, sk->sk_rcvbuf - + READ_ONCE(sk->sk_backlog.len) - atomic_read(&sk->sk_rmem_alloc)); } -- cgit v1.2.3 From 0f31746452e6793ad6271337438af8f4defb8940 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 10 Oct 2019 20:17:41 -0700 Subject: tcp: annotate tp->write_seq lockless reads There are few places where we fetch tp->write_seq while this field can change from IRQ or other cpu. We need to add READ_ONCE() annotations, and also make sure write sides use corresponding WRITE_ONCE() to avoid store-tearing. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/tcp.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/net/tcp.h') diff --git a/include/net/tcp.h b/include/net/tcp.h index 35f6f7e0fdc2..8e7c3f6801a9 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1917,7 +1917,7 @@ static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) static inline bool tcp_stream_memory_free(const struct sock *sk, int wake) { const struct tcp_sock *tp = tcp_sk(sk); - u32 notsent_bytes = tp->write_seq - tp->snd_nxt; + u32 notsent_bytes = READ_ONCE(tp->write_seq) - tp->snd_nxt; return (notsent_bytes << wake) < tcp_notsent_lowat(tp); } -- cgit v1.2.3 From e0d694d638dba768b47be31c22e1a9b4f862f561 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 10 Oct 2019 20:17:42 -0700 Subject: tcp: annotate tp->snd_nxt lockless reads There are few places where we fetch tp->snd_nxt while this field can change from IRQ or other cpu. We need to add READ_ONCE() annotations, and also make sure write sides use corresponding WRITE_ONCE() to avoid store-tearing. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/tcp.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/net/tcp.h') diff --git a/include/net/tcp.h b/include/net/tcp.h index 8e7c3f6801a9..e1d08f69fd39 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1917,7 +1917,8 @@ static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) static inline bool tcp_stream_memory_free(const struct sock *sk, int wake) { const struct tcp_sock *tp = tcp_sk(sk); - u32 notsent_bytes = READ_ONCE(tp->write_seq) - tp->snd_nxt; + u32 notsent_bytes = READ_ONCE(tp->write_seq) - + READ_ONCE(tp->snd_nxt); return (notsent_bytes << wake) < tcp_notsent_lowat(tp); } -- cgit v1.2.3 From ebb3b78db7bf842270a46fd4fe7cc45c78fa5ed6 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 10 Oct 2019 20:17:44 -0700 Subject: tcp: annotate sk->sk_rcvbuf lockless reads For the sake of tcp_poll(), there are few places where we fetch sk->sk_rcvbuf while this field can change from IRQ or other cpu. We need to add READ_ONCE() annotations, and also make sure write sides use corresponding WRITE_ONCE() to avoid store-tearing. Note that other transports probably need similar fixes. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/tcp.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/net/tcp.h') diff --git a/include/net/tcp.h b/include/net/tcp.h index e1d08f69fd39..ab4eb5eb5d07 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1380,14 +1380,14 @@ static inline int tcp_win_from_space(const struct sock *sk, int space) /* Note: caller must be prepared to deal with negative returns */ static inline int tcp_space(const struct sock *sk) { - return tcp_win_from_space(sk, sk->sk_rcvbuf - + return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) - READ_ONCE(sk->sk_backlog.len) - atomic_read(&sk->sk_rmem_alloc)); } static inline int tcp_full_space(const struct sock *sk) { - return tcp_win_from_space(sk, sk->sk_rcvbuf); + return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf)); } extern void tcp_openreq_init_rwin(struct request_sock *req, -- cgit v1.2.3