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=1793827000; b=NVHw8RvYd2h79nfFFzhNR7qJ3xzTB0fHC99Rh9Yxknnsf+QKt4STlVojfhCWE8s8QSAo jz89xqj4NBxP2awbXbF89Rh3T1HdzxcPmsku70W2ZRxjDRD3WwwzT7sxE5pgoIIhp0DEw u80uHFXAvRmtJFrB1ZiTCqz/BN0bCeaLm6if+kMnd+PPMO6Xww/MntkstnyuBEz32PqOW WnkwoR4/H2qx7+5omHvO6zk5gAOxGYNrolcLs7q3JzhwtTQa/90IpyhmjLlwqWNPbi5ZI jlA6O4tmssjwZqxsqa+cssdrIbL5ROO4JqupXk1WP8fYVJJmCbLUz/YSnILpfgz5JYQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793827000; 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=nMk/fHUd17nrUFvRUZq3X5kfpQypf8pgpiMzZvwHvF4=; b=deF/4CL/vlQG2ldan0TFkY9m5PGAUNEwenfJcUME0cuM4jDx04uFmb/Ryhg3D9lMUV2j Q6dYqXTj2alLSU4LRH/pvqzAZb69Dr6CuyqRBmVruxxegfQWYxlutm4bmwneZAcWrcqNK BLFiT+H/oJfWIB67MTAGuKbVgbIOfKw0rMjdreEJKZRONhaBa7Vnn/c7kpNesT62H4KZi hsmKXj5aivbXnQCXyffF8qwbbxk8TeqSTh0rFhjBfeZdXGsZ0YwAPIBHKCblHXL6JWkvv OGibSSOZ/nOMXrztOkjw5GTDKpUGcvyhgxDvm3Ymc65hYW7OQBfm9RcDnyyZS+WUs8A== 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=nNl8mwcg; 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 8E7886074905; Wed, 4 Nov 2026 21:16:40 +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=nNl8mwcg Received: by smtp.kernel.org (Postfix) with ESMTPSA id 213E51F000C1; Wed, 4 Nov 2026 21:16:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793827000; bh=nMk/fHUd17nrUFvRUZq3X5kfpQypf8pgpiMzZvwHvF4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=nNl8mwcgWQj8eu2vBh2VAGapzFzJe4DVdYHfAJG5uNcYIqUatHwsoXZ/0mhboasNy EW6jgdN3ZKXC49h3Lp2tH/3CaI0c4au/YQWZ0Ly03GIQ9LIQicA+k3iLxepXA35isS CVMgPx8h7ubaXtXumRmV0NsGUbbu83R1vVXjBW60= 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 7.3 097/547] serial: core: fix TIOCSSERIAL and TIOCSERCONFIG on uninitialised ports Date: Wed, 4 Nov 2026 16:04:41 -0500 Message-ID: <20261104211040.982049220@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211038.406938024@linuxfoundation.org> References: <20261104211038.406938024@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 7.3-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 6332ed545c899..81a985424694c 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -896,7 +896,11 @@ 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; @@ -1144,7 +1148,8 @@ 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