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 1547F2DF156; Tue, 1 Sep 2026 05:32:00 +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=1788240722; cv=none; b=guj0TEtD6/d+oE+PA6FzIKMWcrte3slsVn5VSC9eyIMCkEA0xZQ4L8I3t9J6RsEt2qJZLuuy0gZERHC4rttF1jPRgBxE5YmZfFTUy1fvAYTAUV9wnxDcVR8jb6b0ffH+ehiKpQNCXdi157OJ3aTQsfdprQ3TrSbHVKGXN9eFIIc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788240722; c=relaxed/simple; bh=5ynHe+dy7ACCQfSkxjgDClc+6VjcbLLhvvl5BxVeuQk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eDkN49AeBBqHgZbJctDEsYjDtNA4fWKC2Tq/qqOkYliPqW8ujwvJkGgPGp9taeiLUtA3Sx6/UCEK+ShxklkKCHuBfcpIDMCfdkKsw2c7YQdJSdKCluh2gRq5jKi5lNf95AgBR93sYIMZ+axuVZ2g89qpleqjTLjf6NIo5w2hRFY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VDqhIoHM; 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="VDqhIoHM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8CDD71F000E9; Tue, 1 Sep 2026 05:31:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788240720; bh=xPgLmERa54izknplIHehdL6mAiqjD6RjdmK9hGApl0o=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=VDqhIoHMX8xIYyWArdGs7ZSdGkaB5eScjNbKYJXZ4PbJFFRDk9aTUfK5rcQOk0uYw cQ8Bme3xjiasYDoJ5P1mb7Ymla+aGZVdaLx3NArdNVo+u+JufYBYZhvHkedHbTdlVL Ny1vPRZSE6eYDYpzgRRpl+x/WcJZ25wJZgrWYtmumkWrmh906G304UMTH5+z1EQ6nP RKQ+ZRXiI6yB9OyCQ2vQyN98sC8voMKVlXsY5yxaOpluxrKu3E71da5oDTeUj9sNfV hZ2fUZeIP6YBzCSqhJtsOS/B2k59MDkEIYPjzWEFzBO1IERfcypiqfDyGNTfUbn+37 PsCei+oUqi22Q== Message-ID: Date: Tue, 1 Sep 2026 07:31:57 +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 1/3] serial: 8250_mxpcie: set the driver data before registering ports To: sashiko-reviews@lists.linux.dev, Linmao Li Cc: linux-serial@vger.kernel.org, Crescent Hsieh References: <20260901041519.114737-1-lilinmao@kylinos.cn> <20260901041519.114737-2-lilinmao@kylinos.cn> <20260901043252.85D391F000E9@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 Sashiko appears to be right. On 01. 09. 26, 6:32, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: > > Pre-existing issues: > - [High] Missing initialization of `up.port.port_id` causes all registered serial ports on a multi-port device to share ID 0 and corrupt each other's hardware state. > - [High] Unprotected read-modify-write on shared hardware register in `mxpcie8250_set_interface` causes a race condition between concurrent operations on adjacent ports. > -- > > commit 0dfacc505133057b054c4b8c8d42d557343c298b > Author: Linmao Li > > serial: 8250_mxpcie: set the driver data before registering ports > > This commit fixes a NULL pointer dereference in the mxpcie8250_rs485_config > callback. It moves pci_set_drvdata() before port registration so the board > data is available when the callback is invoked during initialization. > >> diff --git a/drivers/tty/serial/8250/8250_mxpcie.c b/drivers/tty/serial/8250/8250_mxpcie.c >> index ce873fbd62e93..c0e3517d4e4ec 100644 >> --- a/drivers/tty/serial/8250/8250_mxpcie.c >> +++ b/drivers/tty/serial/8250/8250_mxpcie.c >> @@ -542,6 +542,8 @@ static int mxpcie8250_probe(struct pci_dev *pdev, const struct pci_device_id *id >> >> mxpcie8250_init_board(pdev, priv); >> >> + pci_set_drvdata(pdev, priv); >> + >> up.port.dev = dev; >> up.port.irq = pdev->irq; >> up.port.uartclk = MOXA_PUART_BASE_BAUD * 16; >> @@ -578,7 +580,6 @@ static int mxpcie8250_probe(struct pci_dev *pdev, const struct pci_device_id *id >> } >> priv->port[i].rx_trig_level = MOXA_PUART_RX_TRIG_DEFAULT; >> } >> - pci_set_drvdata(pdev, priv); >> >> return 0; >> } > > [Severity: High] > This isn't a bug introduced by this patch, but while reviewing the port > registration loop, I noticed that mxpcie8250_setup_port() seems to leave > up.port.port_id initialized to 0 for all ports. Because the up structure > is zero-initialized, and up.port.port_id is never assigned the idx value, > it remains 0. > > When this zeroed structure is passed into serial8250_register_8250_port(), > does this cause all registered ports on a multi-port device to share ID 0? > If so, hardware callbacks like mxpcie8250_rs485_config() and > mxpcie8250_startup() that use port->port_id as an index might inadvertently > apply configuration changes to port 0 instead of the intended port. > > [Severity: High] > This is also a pre-existing issue, but looking at mxpcie8250_set_interface(), > the shared hardware register controlling adjacent ports is updated using an > unprotected read-modify-write: > > mxpcie8250_set_interface() > ... > cval = ioread8(uir_addr); > > if (port_idx % 2) > FIELD_MODIFY(MOXA_ODD_RS_MASK, &cval, mode); > else > FIELD_MODIFY(MOXA_EVEN_RS_MASK, &cval, mode); > > iowrite8(cval, uir_addr); > > Since this is called by mxpcie8250_rs485_config(), which is only protected > by the per-port uart_port_lock, could concurrent ioctls on adjacent ports > (like port 0 and port 1) race and corrupt this shared register byte? > -- js suse labs