net/tls: Annotate access to sk_prot with READ_ONCE/WRITE_ONCE
authorJakub Sitnicki <jakub@cloudflare.com>
Tue, 17 Mar 2020 17:04:39 +0000 (18:04 +0100)
committerDavid S. Miller <davem@davemloft.net>
Sun, 22 Mar 2020 03:08:17 +0000 (20:08 -0700)
commitd5bee7374b68de3c44586d46e9e61ffc97a1e886
tree9c1964e017b681e310c7ec48352bd124da90930c
parent5bb4c45d466cb28dd0a7f15f80c4cb7768054e94
net/tls: Annotate access to sk_prot with READ_ONCE/WRITE_ONCE

sockmap performs lockless writes to sk->sk_prot on the following paths:

tcp_bpf_{recvmsg|sendmsg} / sock_map_unref
  sk_psock_put
    sk_psock_drop
      sk_psock_restore_proto
        WRITE_ONCE(sk->sk_prot, proto)

To prevent load/store tearing [1], and to make tooling aware of intentional
shared access [2], we need to annotate other sites that access sk_prot with
READ_ONCE/WRITE_ONCE macros.

Change done with Coccinelle with following semantic patch:

@@
expression E;
identifier I;
struct sock *sk;
identifier sk_prot =~ "^sk_prot$";
@@
(
 E =
-sk->sk_prot
+READ_ONCE(sk->sk_prot)
|
-sk->sk_prot = E
+WRITE_ONCE(sk->sk_prot, E)
|
-sk->sk_prot
+READ_ONCE(sk->sk_prot)
 ->I
)

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/tls/tls_device.c
net/tls/tls_main.c