From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0112E3B6C17; Tue, 21 Jul 2026 22:42:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784673760; cv=none; b=dg2mu+MrJLFPIDdoDZdn4IlTCg7rHUYyy1Hv9sRd+6Ri6+UFafZaqCpLjJlrzkTQeKedD1hMmUBXvZ3h2hhci35Rp5MK8/o7is796bepY6Sq2HcBn2Va25+e/gtAbgZD1KrH3d1Bv6DNCCLv3Of1srpwyNZeOU/rBfg6EXAkiQ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784673760; c=relaxed/simple; bh=IlK1l8bEMZjlUAL/xbbnurjFW+MnAxCZgXCu0KQ7DrU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DdYYvALk7At8mDsipbagJattySyzzJDvC/KRU7NbpR95Fwouc643chgXjae8sJIu8lrFNVWPYLRBK1DEHscgsR2GzuSNTCXoP1kCfG4AZaH2whsnJPUlzPrMsr97r6xgMbd6Bi+/uk662aOLUUdqA03WHj5MPWSOp9Lh/8P0S68= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=nyTCch74; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="nyTCch74" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 619FA1F000E9; Tue, 21 Jul 2026 22:42:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784673758; bh=3X43Yae0/89OWrK2KcjxKcN+VRQqDilHtN/cWQcwMis=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=nyTCch74JN/d6gMhpRX5xsYHkzKOXVO2PMgbGEg/dw/S6hjK+p5G+mPdiPKGUfMtS sRj71J1qZAF22qgHrBi8xPRVdpIbWtDuJHSgyqL1WnYJuPNXU0kdTWcgVV/U6aWYIZ ov1nsC9OzaO5BxC9LAsNFQ5O6LR6nCWWDMMX4K7c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Runyu Xiao , Paolo Abeni , Sasha Levin Subject: [PATCH 5.10 267/699] kcm: use WRITE_ONCE() when changing lower socket callbacks Date: Tue, 21 Jul 2026 17:20:26 +0200 Message-ID: <20260721152401.725615069@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152355.667394603@linuxfoundation.org> References: <20260721152355.667394603@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Runyu Xiao [ Upstream commit 47186409c092cd7dd70350999186c700233e854d ] 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: ab7ac4eb9832 ("kcm: Kernel Connection Multiplexor module") Signed-off-by: Runyu Xiao Link: https://patch.msgid.link/20260611053543.2429462-1-runyu.xiao@seu.edu.cn Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/kcm/kcmsock.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c index 2f2840aa4a8129..df3ca6a9791e6c 100644 --- a/net/kcm/kcmsock.c +++ b/net/kcm/kcmsock.c @@ -1404,8 +1404,8 @@ 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); @@ -1481,8 +1481,8 @@ 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); -- 2.53.0