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 651EC2E3382; Tue, 15 Jul 2025 13:57:53 +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=1752587873; cv=none; b=ZRC//dLlmrlswUEuQKfa0a8D1KWn+nYBidIl2+px3A4ycSG6+QBO3qvArUP60JpqeQ7F9BR1xx04keEicswcKQXgVTbDsy1cHYRAnYW7Qs7Pj6BxDvxX6ab5BMmC4BoHTOQCdjhPSWKVG3IsiOozFdFjhB+92OoILbmvDmWKDXM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752587873; c=relaxed/simple; bh=szJ++SjUKi5ZspnwmI5hf61rNbDdlN3qw7Dpq4d2zyk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sLGaNHt1ddbcu0VM2+8nWZ9L/iIuO/zpJvriV19dzFfpfwyi3G7zktNkxciOL50YSUi0IcXnaqGAf+6mE1vOk5FG9zZPmAQA6KqhfpN0DjPuQ8F4bIoXcev4WhOTSsYC9Y6c8jDae133+FrmvuVUbI3abt+YVEWUA7YKRJ/aVpU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=n0BYg1xy; 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="n0BYg1xy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F63BC4CEE3; Tue, 15 Jul 2025 13:57:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1752587873; bh=szJ++SjUKi5ZspnwmI5hf61rNbDdlN3qw7Dpq4d2zyk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=n0BYg1xyetsAracFyN9wX/ZQMcJssfqZ4qzj02KNmTHwOGsHYyt7fX6yBLAENl62Q bPH+MJAOYVqaaxXxiaVZHk9NYyR7k01ddfYKj37elRkbgUS4wdNGR4CYpmKqJCJfRK tR9vA3wDF1GF/Dx1o71BLIG+oym38VF7OopvKngs= 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 5.10 176/208] usb: gadget: u_serial: Fix race condition in TTY wakeup Date: Tue, 15 Jul 2025 15:14:45 +0200 Message-ID: <20250715130818.018714848@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250715130810.830580412@linuxfoundation.org> References: <20250715130810.830580412@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 5.10-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 @@ -292,8 +292,8 @@ __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; } @@ -570,7 +570,7 @@ 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) {