From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 0CBE12E7F03; Tue, 15 Jul 2025 13:47:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752587267; cv=none; b=jkyl08G4NYHJxfEUP2GzUPVVzZ2kpCI8CXhw5DYh3KzORHbxJYDC2KoU6EwRcBIk49Xt6gS5cjnL6+N97YpfrNAeX8fjqA/7ffAgxP24TBFFxdu91ISbkrzU7QOhQR8V2Zm/w6oLvPBaFK+jkGM3sgZQCrnXPuxfUpPWb+1RPtc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752587267; c=relaxed/simple; bh=6Z7rp4/zoQaICpC/rxnHfgIkvtSxYbVRz92FbZilUkk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=B7LGAB6ot5Ri2GNmHKkfuwJEPRSe0TjMi4YR4iidbfVIpP6BzLqlWbVfihU4PlPx5cJVPin+lAXumVaVzfcQTwhCuQvuHeGRElA7c9b3eYepLHzP50fgT74xuiNTR1BmzPL0xTonByS5UcLJ9x1IOcvYRq6YnA7ieWzKG/yY/I8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=mzR7aHe9; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="mzR7aHe9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 95AD7C4CEF1; Tue, 15 Jul 2025 13:47:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1752587266; bh=6Z7rp4/zoQaICpC/rxnHfgIkvtSxYbVRz92FbZilUkk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mzR7aHe9pOMkZ/mlUypMnQVlQHHIYviK19c/u8voqvv6ch3rpy7V3IOxx4ksPwD9j KYun9wmxnyUFU6BBKKd1Xy4ndpgqgRc2bPIKYrAVpkQEqC/8mMTb6QGjcY5qk3w0U8 PTZd9C3v8hNVMkY4birXZ0D22UMmjVneITLHguoE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Kuen-Han Tsai , Prashanth K Subject: [PATCH 6.1 35/88] usb: gadget: u_serial: Fix race condition in TTY wakeup Date: Tue, 15 Jul 2025 15:14:11 +0200 Message-ID: <20250715130755.929787003@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250715130754.497128560@linuxfoundation.org> References: <20250715130754.497128560@linuxfoundation.org> User-Agent: quilt/0.68 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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuen-Han Tsai commit c529c3730bd09115684644e26bf01ecbd7e2c2c9 upstream. A race condition occurs when gs_start_io() calls either gs_start_rx() or gs_start_tx(), as those functions briefly drop the port_lock for usb_ep_queue(). This allows gs_close() and gserial_disconnect() to clear port.tty and port_usb, respectively. Use the null-safe TTY Port helper function to wake up TTY. Example CPU1: CPU2: gserial_connect() // lock gs_close() // await lock gs_start_rx() // unlock usb_ep_queue() gs_close() // lock, reset port.tty and unlock gs_start_rx() // lock tty_wakeup() // NPE Fixes: 35f95fd7f234 ("TTY: usb/u_serial, use tty from tty_port") Cc: stable Signed-off-by: Kuen-Han Tsai Reviewed-by: Prashanth K Link: https://lore.kernel.org/linux-usb/20240116141801.396398-1-khtsai@google.com/ Link: https://lore.kernel.org/r/20250617050844.1848232-2-khtsai@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/u_serial.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -290,8 +290,8 @@ __acquires(&port->port_lock) break; } - if (do_tty_wake && port->port.tty) - tty_wakeup(port->port.tty); + if (do_tty_wake) + tty_port_tty_wakeup(&port->port); return status; } @@ -568,7 +568,7 @@ static int gs_start_io(struct gs_port *p gs_start_tx(port); /* Unblock any pending writes into our circular buffer, in case * we didn't in gs_start_tx() */ - tty_wakeup(port->port.tty); + tty_port_tty_wakeup(&port->port); } else { /* Free reqs only if we are still connected */ if (port->port_usb) {