From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793831310; b=PKG8JyN5Q9vakvNbCH5nXj1ZEKybg3QatKTIJ78WwLbSzICs8gRrfYBaLEcF7Yvodroa QzuDGty1khVPZ0udng8gaUOTFIoUoo+T6d0zyxqyOMG1KyYcJYG0vAG0pL/jjAPX93XpM /l7Mn1q+GTZZPsfSuq/xu7BmeUWna0mUbwm9UL7jAs0gMhpREBnWXqXNaXqW/4s1O024c WWSyRuWLi2mgkacYJ5885bpG2cF71AZcFaQG4YGU26wQoqBziuX0O2jdHBlOmQyvF1Qjf I76aouq1RZL/Yu0Wu0JoF4BcLyn8DEhW75R0HXX4sxtGpXhJD+cuwkyJD2IxeoLeB4A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831310; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=31/Yvkr4k42SY+LKft/NS19AZhms1xZKfoRkam+TLlo=; b=khAW4dldcG9vycDaUu1kIPYl9eTQaikielRmmoSAtWL8hGn5TEHX54RdxYTdHVanFO7K JmbciSiplXaJGKK7DYIPdPNGMbsHyek2WGNSxTyFI9t/vsxz5n4dx6JzZQmQ9XO75fJLi C2EujRSXCaUP6Hg6RuixcwlXY841DYJTUvX7XfiwSW9qyBpECB80Va6aQnuWmjxIbkT2C Ael0lH7kDm0PpyHoZQKKVYIXkIeq2fvBSiidXEIaOiJCuAfh6OcEklVJ/ZXLjTuQCjUyU RtKf8rCI9eu1uy0FcqIQyis0Cxlj74lR2vp4PoMujbl75WG6LbEuOlWcMO3VmqU2SUA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=zpYj98m3; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 70000606B2F8; Wed, 4 Nov 2026 22:28:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=zpYj98m3 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0BA641F00919; Wed, 4 Nov 2026 22:28:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831310; bh=31/Yvkr4k42SY+LKft/NS19AZhms1xZKfoRkam+TLlo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=zpYj98m3SjWA0hIJXdrequQzyxNoh9DUTYOMreCmATyLBIeTYfjmSOg0vH4WQwnc7 u25lbOgIA/fkpbP1qfh/FJXEmnFLFCzF7+RhWIls3P0hi9YvxKJr7pBIfYPYSSmkm2 Fx8XhBq1AFK2IKgCviaTJlv7Jhl63UeV4QIMF6YA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable@kernel.org, Hengyu Liang , Johan Hovold , Sasha Levin Subject: [PATCH 6.18 0625/1005] serial: core: fix TIOCSSERIAL and TIOCSERCONFIG on uninitialised ports Date: Wed, 4 Nov 2026 16:05:58 -0500 Message-ID: <20261104211101.312952653@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hengyu Liang [ Upstream commit e1f46a09df93650288babb23de6e34bff73e80e6 ] Commit 8ca59f7baee7 ("serial: fix ioctl hangup race") made uart_set_info() and uart_do_autoconfig() return -EIO when TTY_IO_ERROR is set, so that they do not run on a port that has been hung up. However, TTY_IO_ERROR is also set on a port that could not be started, for example because its type is unknown, and by uart_shutdown(), which both functions call. As of now, setserial cannot configure a port that the kernel did not detect, and an autoconfig that follows a port, irq or type change in the same setserial call fails on any port. The issue can be reproduced with setserial (busybox) on a port without a detected UART, for example ttyS3 of a QEMU guest: setserial /dev/ttyS3 uart 16550A setserial -g /dev/ttyS3 Before commit 8ca59f7baee7 ("serial: fix ioctl hangup race"), the result is: /dev/ttyS3, UART: 16550A, Port: 0x02e8, IRQ: 3 After that commit, the result is: setserial: can't set serial info: Input/output error /dev/ttyS3, UART: unknown, Port: 0x02e8, IRQ: 3 This patch will check tty_port_active() in these two functions instead. uart_hangup() clears it under the port mutex, and it stays set on an open port that could not be started. Fixes: 8ca59f7baee7 ("serial: fix ioctl hangup race") Cc: stable@kernel.org Signed-off-by: Hengyu Liang Tested-by: Johan Hovold Reviewed-by: Johan Hovold Link: https://patch.msgid.link/20261010034616.3915864-1-hengyul@cs.unc.edu Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/serial_core.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 80d1a1b0ba9c1..c12402effafe8 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -899,7 +899,11 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port, upf_t old_flags, new_flags; int retval; - if (!uport || tty_io_error(tty)) + /* + * TTY_IO_ERROR is also set on a port that could not be started, and + * this is how such a port is configured. Only refuse a hung up port. + */ + if (!uport || !tty_port_active(port)) return -EIO; new_port = new_info->port; @@ -1151,7 +1155,8 @@ static int uart_do_autoconfig(struct tty_struct *tty, struct uart_state *state) */ scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &port->mutex) { uport = uart_port_check(state); - if (!uport || tty_io_error(tty)) + /* As in uart_set_info(), only refuse a hung up port. */ + if (!uport || !tty_port_active(port)) return -EIO; if (tty_port_users(port) != 1) -- 2.53.0