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authorEric Dumazet <edumazet@google.com>2022-02-17 09:05:02 -0800
committerDavid S. Miller <davem@davemloft.net>2022-02-18 11:14:52 +0000
commita1cdec57e03a1352e92fbbe7974039dda4efcec0 (patch)
treea2c86848fa1b5cab3677218258bce83b8dab4dc4 /net/core
parente9da0b56fe27206b49f39805f7dcda8a89379062 (diff)
downloadlinux-a1cdec57e03a1352e92fbbe7974039dda4efcec0.tar.bz2
net-timestamp: convert sk->sk_tskey to atomic_t
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 <edumazet@google.com> Cc: Willem de Bruijn <willemb@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/skbuff.c2
-rw-r--r--net/core/sock.c4
2 files changed, 3 insertions, 3 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 9d0388bed0c1..6a15ce3eb1d3 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -4730,7 +4730,7 @@ static void __skb_complete_tx_timestamp(struct sk_buff *skb,
if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) {
serr->ee.ee_data = skb_shinfo(skb)->tskey;
if (sk_is_tcp(sk))
- 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 4ff806d71921..6eb174805bf0 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -879,9 +879,9 @@ 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);
}
}