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>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index 1c5574e2e058..a562ebaaa33c 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -366,7 +366,7 @@ static int tls_do_allocation(struct sock *sk,
 	if (!offload_ctx->open_record) {
 		if (unlikely(!skb_page_frag_refill(prepend_size, pfrag,
 						   sk->sk_allocation))) {
-			sk->sk_prot->enter_memory_pressure(sk);
+			READ_ONCE(sk->sk_prot)->enter_memory_pressure(sk);
 			sk_stream_moderate_sndbuf(sk);
 			return -ENOMEM;
 		}