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net: Annotate sk->sk_write_space() for UDP SOCKMAP.

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UDP TX skb->destructor() is sock_wfree(), and UDP holds lock_sock()
only for UDP_CORK / MSG_MORE sendmsg().

Otherwise, sk->sk_write_space() may be read locklessly while SOCKMAP
rewrites sk->sk_write_space().

Let's use WRITE_ONCE() and READ_ONCE() for sk->sk_write_space().

Note that the write side is annotated by commit 2ef2b20cf4
("net: annotate data-races around sk->sk_{data_ready,write_space}").

Fixes: 7b98cd42b0 ("bpf: sockmap: Add UDP support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://patch.msgid.link/20260529193941.3897256-1-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2026-05-29 19:39:23 +00:00 committed by Jakub Kicinski
parent 73bf3cca7d
commit b748765019
1 changed files with 6 additions and 2 deletions
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8
net/core/sock.c
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@ -2676,8 +2676,12 @@ void sock_wfree(struct sk_buff *skb)
int old;
if (!sock_flag(sk, SOCK_USE_WRITE_QUEUE)) {
void (*sk_write_space)(struct sock *sk);
sk_write_space = READ_ONCE(sk->sk_write_space);
if (sock_flag(sk, SOCK_RCU_FREE) &&
sk->sk_write_space == sock_def_write_space) {
sk_write_space == sock_def_write_space) {
rcu_read_lock();
free = __refcount_sub_and_test(len, &sk->sk_wmem_alloc,
&old);
@ -2693,7 +2697,7 @@ void sock_wfree(struct sk_buff *skb)
* after sk_write_space() call
*/
WARN_ON(refcount_sub_and_test(len - 1, &sk->sk_wmem_alloc));
sk->sk_write_space(sk);
sk_write_space(sk);
len = 1;
}
/*