From ff999198ec2149a6b83edb083293c91ec027f56f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 17 Feb 2022 09:05:02 -0800 Subject: [PATCH] net-timestamp: convert sk->sk_tskey to atomic_t [ Upstream commit a1cdec57e03a1352e92fbbe7974039dda4efcec0 ] UDP sendmsg() can be lockless, this is causing all kinds of data races. This patch converts sk->sk_tskey to remove one of these races. BUG: KCSAN: data-race in __ip_append_data / __ip_append_data read to 0xffff8881035d4b6c of 4 bytes by task 8877 on cpu 1: __ip_append_data+0x1c1/0x1de0 net/ipv4/ip_output.c:994 ip_make_skb+0x13f/0x2d0 net/ipv4/ip_output.c:1636 udp_sendmsg+0x12bd/0x14c0 net/ipv4/udp.c:1249 inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:819 sock_sendmsg_nosec net/socket.c:705 [inline] sock_sendmsg net/socket.c:725 [inline] ____sys_sendmsg+0x39a/0x510 net/socket.c:2413 ___sys_sendmsg net/socket.c:2467 [inline] __sys_sendmmsg+0x267/0x4c0 net/socket.c:2553 __do_sys_sendmmsg net/socket.c:2582 [inline] __se_sys_sendmmsg net/socket.c:2579 [inline] __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2579 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae write to 0xffff8881035d4b6c of 4 bytes by task 8880 on cpu 0: __ip_append_data+0x1d8/0x1de0 net/ipv4/ip_output.c:994 ip_make_skb+0x13f/0x2d0 net/ipv4/ip_output.c:1636 udp_sendmsg+0x12bd/0x14c0 net/ipv4/udp.c:1249 inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:819 sock_sendmsg_nosec net/socket.c:705 [inline] sock_sendmsg net/socket.c:725 [inline] ____sys_sendmsg+0x39a/0x510 net/socket.c:2413 ___sys_sendmsg net/socket.c:2467 [inline] __sys_sendmmsg+0x267/0x4c0 net/socket.c:2553 __do_sys_sendmmsg net/socket.c:2582 [inline] __se_sys_sendmmsg net/socket.c:2579 [inline] __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2579 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0x0000054d -> 0x0000054e Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 8880 Comm: syz-executor.5 Not tainted 5.17.0-rc2-syzkaller-00167-gdcb85f85fa6f-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Fixes: 09c2d251b707 ("net-timestamp: add key to disambiguate concurrent datagrams") Signed-off-by: Eric Dumazet Cc: Willem de Bruijn Reported-by: syzbot Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- include/net/sock.h | 4 ++-- net/can/j1939/transport.c | 2 +- net/core/skbuff.c | 2 +- net/core/sock.c | 4 ++-- net/ipv4/ip_output.c | 2 +- net/ipv6/ip6_output.c | 2 +- 6 files changed, 8 insertions(+), 8 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index dfb92f9..7d49196 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -506,7 +506,7 @@ struct sock { u16 sk_tsflags; int sk_bind_phc; u8 sk_shutdown; - u32 sk_tskey; + atomic_t sk_tskey; atomic_t sk_zckey; u8 sk_clockid; @@ -2598,7 +2598,7 @@ static inline void _sock_tx_timestamp(struct sock *sk, __u16 tsflags, __sock_tx_timestamp(tsflags, tx_flags); if (tsflags & SOF_TIMESTAMPING_OPT_ID && tskey && tsflags & SOF_TIMESTAMPING_TX_RECORD_MASK) - *tskey = sk->sk_tskey++; + *tskey = atomic_inc_return(&sk->sk_tskey) - 1; } if (unlikely(sock_flag(sk, SOCK_WIFI_STATUS))) *tx_flags |= SKBTX_WIFI_STATUS; diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c index a271688..307ee11 100644 --- a/net/can/j1939/transport.c +++ b/net/can/j1939/transport.c @@ -2006,7 +2006,7 @@ struct j1939_session *j1939_tp_send(struct j1939_priv *priv, /* set the end-packet for broadcast */ session->pkt.last = session->pkt.total; - skcb->tskey = session->sk->sk_tskey++; + skcb->tskey = atomic_inc_return(&session->sk->sk_tskey) - 1; session->tskey = skcb->tskey; return session; diff --git a/net/core/skbuff.c b/net/core/skbuff.c index bb4dce8..449a96e 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4844,7 +4844,7 @@ static void __skb_complete_tx_timestamp(struct sk_buff *skb, serr->ee.ee_data = skb_shinfo(skb)->tskey; if (sk->sk_protocol == IPPROTO_TCP && sk->sk_type == SOCK_STREAM) - serr->ee.ee_data -= sk->sk_tskey; + serr->ee.ee_data -= atomic_read(&sk->sk_tskey); } err = sock_queue_err_skb(sk, skb); diff --git a/net/core/sock.c b/net/core/sock.c index 6ea317f..deaed1b 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -866,9 +866,9 @@ int sock_set_timestamping(struct sock *sk, int optname, if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) return -EINVAL; - sk->sk_tskey = tcp_sk(sk)->snd_una; + atomic_set(&sk->sk_tskey, tcp_sk(sk)->snd_una); } else { - sk->sk_tskey = 0; + atomic_set(&sk->sk_tskey, 0); } } diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index a4d2eb6..131066d 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -992,7 +992,7 @@ static int __ip_append_data(struct sock *sk, if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP && sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) - tskey = sk->sk_tskey++; + tskey = atomic_inc_return(&sk->sk_tskey) - 1; hh_len = LL_RESERVED_SPACE(rt->dst.dev); diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index ff4e83e..22bf8fb 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1465,7 +1465,7 @@ static int __ip6_append_data(struct sock *sk, if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP && sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) - tskey = sk->sk_tskey++; + tskey = atomic_inc_return(&sk->sk_tskey) - 1; hh_len = LL_RESERVED_SPACE(rt->dst.dev); -- 2.7.4