github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-28 10:09:10 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

kcm: use WRITE_ONCE() when changing lower socket callbacks

Browse Source 
kcm_attach() replaces a live lower TCP socket's sk_data_ready and
sk_write_space callbacks with KCM handlers, and kcm_unattach() restores
them later. Those callback-pointer updates are still plain stores even
though the same fields can be read and invoked concurrently on other
CPUs.

If another CPU observes an older callback snapshot after the live field
has already been restored, callback execution can run with a mismatched
target and sk_user_data state, leading to stale or misdirected wakeups.

Use WRITE_ONCE() for the callback replacement and restore operations so
these shared callback fields follow the same visibility contract already
established by the earlier 4022 fixes.

Fixes: ab7ac4eb98 ("kcm: Kernel Connection Multiplexor module")
Signed-off-by: Runyu Xiao <runyu.xiao@seu.edu.cn>
Link: https://patch.msgid.link/20260611053543.2429462-1-runyu.xiao@seu.edu.cn
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Runyu Xiao 2026-06-11 13:35:43 +08:00 committed by Paolo Abeni
parent a4004aa0de
commit 47186409c0
1 changed files with 4 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
net/kcm/kcmsock.c
View File

@ -1304,8 +1304,8 @@ static int kcm_attach(struct socket *sock, struct socket *csock,
psock->save_write_space = csk->sk_write_space;
psock->save_state_change = csk->sk_state_change;
csk->sk_user_data = psock;
csk->sk_data_ready = psock_data_ready;
csk->sk_write_space = psock_write_space;
WRITE_ONCE(csk->sk_data_ready, psock_data_ready);
WRITE_ONCE(csk->sk_write_space, psock_write_space);
csk->sk_state_change = psock_state_change;
write_unlock_bh(&csk->sk_callback_lock);
@ -1381,8 +1381,8 @@ static void kcm_unattach(struct kcm_psock *psock)
*/
write_lock_bh(&csk->sk_callback_lock);
csk->sk_user_data = NULL;
csk->sk_data_ready = psock->save_data_ready;
csk->sk_write_space = psock->save_write_space;
WRITE_ONCE(csk->sk_data_ready, psock->save_data_ready);
WRITE_ONCE(csk->sk_write_space, psock->save_write_space);
csk->sk_state_change = psock->save_state_change;
strp_stop(&psock->strp);