diff options
| author | Kuniyuki Iwashima | 2022-10-06 11:53:49 -0700 |
|---|---|---|
| committer | Jakub Kicinski | 2022-10-12 17:50:37 -0700 |
| commit | f49cd2f4d6170d27a2c61f1fecb03d8a70c91f57 (patch) | |
| tree | 4950aa7712d9acefbff34efec23105915293f8c8 /net/ipv6 | |
| parent | 364f997b5cfe1db0d63a390fe7c801fa2b3115f6 (diff) | |
tcp: Fix data races around icsk->icsk_af_ops.
setsockopt(IPV6_ADDRFORM) and tcp_v6_connect() change icsk->icsk_af_ops
under lock_sock(), but tcp_(get|set)sockopt() read it locklessly. To
avoid load/store tearing, we need to add READ_ONCE() and WRITE_ONCE()
for the reads and writes.
Thanks to Eric Dumazet for providing the syzbot report:
BUG: KCSAN: data-race in tcp_setsockopt / tcp_v6_connect
write to 0xffff88813c624518 of 8 bytes by task 23936 on cpu 0:
tcp_v6_connect+0x5b3/0xce0 net/ipv6/tcp_ipv6.c:240
__inet_stream_connect+0x159/0x6d0 net/ipv4/af_inet.c:660
inet_stream_connect+0x44/0x70 net/ipv4/af_inet.c:724
__sys_connect_file net/socket.c:1976 [inline]
__sys_connect+0x197/0x1b0 net/socket.c:1993
__do_sys_connect net/socket.c:2003 [inline]
__se_sys_connect net/socket.c:2000 [inline]
__x64_sys_connect+0x3d/0x50 net/socket.c:2000
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
read to 0xffff88813c624518 of 8 bytes by task 23937 on cpu 1:
tcp_setsockopt+0x147/0x1c80 net/ipv4/tcp.c:3789
sock_common_setsockopt+0x5d/0x70 net/core/sock.c:3585
__sys_setsockopt+0x212/0x2b0 net/socket.c:2252
__do_sys_setsockopt net/socket.c:2263 [inline]
__se_sys_setsockopt net/socket.c:2260 [inline]
__x64_sys_setsockopt+0x62/0x70 net/socket.c:2260
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
value changed: 0xffffffff8539af68 -> 0xffffffff8539aff8
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23937 Comm: syz-executor.5 Not tainted
6.0.0-rc4-syzkaller-00331-g4ed9c1e971b1-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 08/26/2022
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzbot <syzkaller@googlegroups.com>
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/ipv6_sockglue.c | 3 | ||||
| -rw-r--r-- | net/ipv6/tcp_ipv6.c | 6 |
2 files changed, 6 insertions, 3 deletions
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index d7207a546aec..532f4478c884 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -479,7 +479,8 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname, /* Paired with READ_ONCE(sk->sk_prot) in inet6_stream_ops */ WRITE_ONCE(sk->sk_prot, &tcp_prot); - icsk->icsk_af_ops = &ipv4_specific; + /* Paired with READ_ONCE() in tcp_(get|set)sockopt() */ + WRITE_ONCE(icsk->icsk_af_ops, &ipv4_specific); sk->sk_socket->ops = &inet_stream_ops; sk->sk_family = PF_INET; tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index a8adda623da1..2a3f9296df1e 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -238,7 +238,8 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr, sin.sin_port = usin->sin6_port; sin.sin_addr.s_addr = usin->sin6_addr.s6_addr32[3]; - icsk->icsk_af_ops = &ipv6_mapped; + /* Paired with READ_ONCE() in tcp_(get|set)sockopt() */ + WRITE_ONCE(icsk->icsk_af_ops, &ipv6_mapped); if (sk_is_mptcp(sk)) mptcpv6_handle_mapped(sk, true); sk->sk_backlog_rcv = tcp_v4_do_rcv; @@ -250,7 +251,8 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr, if (err) { icsk->icsk_ext_hdr_len = exthdrlen; - icsk->icsk_af_ops = &ipv6_specific; + /* Paired with READ_ONCE() in tcp_(get|set)sockopt() */ + WRITE_ONCE(icsk->icsk_af_ops, &ipv6_specific); if (sk_is_mptcp(sk)) mptcpv6_handle_mapped(sk, false); sk->sk_backlog_rcv = tcp_v6_do_rcv; |