From: Eric Dumazet Date: Tue, 3 Oct 2023 18:34:55 +0000 (+0000) Subject: netlink: annotate data-races around sk->sk_err X-Git-Tag: v6.6-rc5~22^2~5 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d0f95894fda7d4f895b29c1097f92d7fee278cb2;p=thirdparty%2Flinux.git netlink: annotate data-races around sk->sk_err syzbot caught another data-race in netlink when setting sk->sk_err. Annotate all of them for good measure. BUG: KCSAN: data-race in netlink_recvmsg / netlink_recvmsg write to 0xffff8881613bb220 of 4 bytes by task 28147 on cpu 0: netlink_recvmsg+0x448/0x780 net/netlink/af_netlink.c:1994 sock_recvmsg_nosec net/socket.c:1027 [inline] sock_recvmsg net/socket.c:1049 [inline] __sys_recvfrom+0x1f4/0x2e0 net/socket.c:2229 __do_sys_recvfrom net/socket.c:2247 [inline] __se_sys_recvfrom net/socket.c:2243 [inline] __x64_sys_recvfrom+0x78/0x90 net/socket.c:2243 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd write to 0xffff8881613bb220 of 4 bytes by task 28146 on cpu 1: netlink_recvmsg+0x448/0x780 net/netlink/af_netlink.c:1994 sock_recvmsg_nosec net/socket.c:1027 [inline] sock_recvmsg net/socket.c:1049 [inline] __sys_recvfrom+0x1f4/0x2e0 net/socket.c:2229 __do_sys_recvfrom net/socket.c:2247 [inline] __se_sys_recvfrom net/socket.c:2243 [inline] __x64_sys_recvfrom+0x78/0x90 net/socket.c:2243 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd value changed: 0x00000000 -> 0x00000016 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 28146 Comm: syz-executor.0 Not tainted 6.6.0-rc3-syzkaller-00055-g9ed22ae6be81 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet Reported-by: syzbot Reviewed-by: Simon Horman Link: https://lore.kernel.org/r/20231003183455.3410550-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 642b9d382fb46..eb086b06d60da 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -352,7 +352,7 @@ static void netlink_overrun(struct sock *sk) if (!nlk_test_bit(RECV_NO_ENOBUFS, sk)) { if (!test_and_set_bit(NETLINK_S_CONGESTED, &nlk_sk(sk)->state)) { - sk->sk_err = ENOBUFS; + WRITE_ONCE(sk->sk_err, ENOBUFS); sk_error_report(sk); } } @@ -1605,7 +1605,7 @@ static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p) goto out; } - sk->sk_err = p->code; + WRITE_ONCE(sk->sk_err, p->code); sk_error_report(sk); out: return ret; @@ -1991,7 +1991,7 @@ static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) { ret = netlink_dump(sk); if (ret) { - sk->sk_err = -ret; + WRITE_ONCE(sk->sk_err, -ret); sk_error_report(sk); } } @@ -2511,7 +2511,7 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, err_bad_put: nlmsg_free(skb); err_skb: - NETLINK_CB(in_skb).sk->sk_err = ENOBUFS; + WRITE_ONCE(NETLINK_CB(in_skb).sk->sk_err, ENOBUFS); sk_error_report(NETLINK_CB(in_skb).sk); } EXPORT_SYMBOL(netlink_ack);