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 7EDAB25A321; Tue, 1 Sep 2026 05:33:07 +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=1788240788; cv=none; b=MJF/rTJI5hmGwHdsngN2bT8GgOBQ4jSYbfsSCXtsgdKVp+syAChYULiNn+OsEtPsainspVNIv6zOYStz+1fXW3eqTsa5h14S4ZJe/AAt+SPFYd6n2PRs3S5Jf+1zWUbSGIJlL17/LoGnRM1aJEiuwieoyi1X72a9/ViJqPaeVuM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788240788; c=relaxed/simple; bh=5vcoJ8AO/cySm9bp2yDK3GUIlsc1AOb0ydLyZa28uTM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=G87Slzd9SqTmxMYa/0k3bYhcc8RDfuyV+weplSVU+Mmd/MT6OarnxJ0rcn8yRV7S5/AXdxW06MwvuisHtYU2SGysv2vOOQ5wv5dr3O3JINCNKZw7Yfea4MvE0u9IHkMzRu+fjJ5rtSNqm2ajPOB0bmbV/5V8nBgKsdBm2SGI9BI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ieT9qjUH; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ieT9qjUH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 555051F000E9; Tue, 1 Sep 2026 05:33:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788240787; bh=ZjUDUieFw3qEpklR8NkqsmcdGESAV2KdFsPmKNcH9pU=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=ieT9qjUHRUJO5pu1XcW7ZaXZGv3MH7gTMz3OMV1gphb72DFpvN9c2mlmHDaOlGXRN GTIRuGNyfUnVel5fFD6rs1aSuxHZKD8jY4iLqoOnGcKZuEN1+F3g56WHHyrWvcsjGp nKg5jQgvamWF7fvQCRIa8ozL2mQXzvNU5A4oto2v/W/CzK5KHul4820jJIVUkDVE0G gXEwfYm5fDpVb52OLaoKUEfOBt7DRmVatAjaXuGJ7yMVPaZYSwsfssEh+K2ar/TKGr uUTZv4/NjEU+S1LXto5BKHgz4i0mB6XUWWzovppOR+yiDns8iRlED5/haGPvQ02mXr LQxlYmGp7qXzg== Message-ID: Date: Tue, 1 Sep 2026 07:33:04 +0200 Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/3] serial: 8250_mxpcie: take the line settings from the new termios To: sashiko-reviews@lists.linux.dev, Linmao Li Cc: linux-serial@vger.kernel.org, Crescent CY Hsieh References: <20260901041519.114737-1-lilinmao@kylinos.cn> <20260901041519.114737-4-lilinmao@kylinos.cn> <20260901042326.F3AE41F000E9@smtp.kernel.org> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit CC Crescent as well. On 01. 09. 26, 6:23, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > > Pre-existing issues: > - [High] Hardware registers and port status are modified without holding the port lock or a Runtime PM reference. > -- > > commit cc8d50f2957c7d540f5a4840cf6ed31ccd1bed47 > Author: Linmao Li > > serial: 8250_mxpcie: take the line settings from the new termios > > mxpcie8250_set_termios() reads the line settings out of port->state->port.tty, > which is only set once the port has been opened. This commit fixes a NULL > dereference during console setup or kgdboc attach by reading the settings > from the termios the serial core passes in instead. > >> diff --git a/drivers/tty/serial/8250/8250_mxpcie.c b/drivers/tty/serial/8250/8250_mxpcie.c >> index ef2516ec16da0..19f1f51eec477 100644 >> --- a/drivers/tty/serial/8250/8250_mxpcie.c >> +++ b/drivers/tty/serial/8250/8250_mxpcie.c >> @@ -218,8 +218,6 @@ static void mxpcie8250_set_termios(struct uart_port *port, >> const struct ktermios *old) >> { >> struct uart_8250_port *up = up_to_u8250p(port); >> - struct tty_struct *tty = port->state->port.tty; >> - unsigned int cflag = tty->termios.c_cflag; >> u8 efr, val; >> >> serial8250_do_set_termios(port, new, old); >> @@ -229,23 +227,25 @@ static void mxpcie8250_set_termios(struct uart_port *port, >> efr = serial_in(up, MOXA_PUART_EFR); > > [Severity: High] > This is a pre-existing issue, but is it safe to modify the port status and > access hardware registers here after serial8250_do_set_termios() has > already released the port lock and runtime PM reference? > > Modifying up->port.status in mxpcie8250_set_termios() without holding the > port lock creates a data race that can corrupt flow control flags > (e.g., UPSTAT_AUTOCTS). This directly violates the locking contract > documented in include/linux/serial_core.h. > > Furthermore, accessing UART hardware registers via serial_in() and > serial_out() without a port lock or a Runtime PM reference can lead to > concurrent register access races with IRQ handlers, or bus faults if the > device enters a suspended state. This sequence occurs every time > mxpcie8250_set_termios() is called, for instance when userspace calls > tcsetattr to change flow control on the TTY device. > >> efr &= ~(MOXA_PUART_EFR_AUTO_RTS | MOXA_PUART_EFR_AUTO_CTS); >> >> - if (cflag & CRTSCTS) { >> + if (new->c_cflag & CRTSCTS) { >> efr |= (MOXA_PUART_EFR_AUTO_RTS | MOXA_PUART_EFR_AUTO_CTS); >> up->port.status |= (UPSTAT_AUTORTS | UPSTAT_AUTOCTS); >> } > -- js suse labs