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 22D9C430789; Thu, 30 Jul 2026 15:44:58 +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=1785426299; cv=none; b=Mjz/UYOTfCes6oDpUw6QpAJSeMXAV7BVnljXxl32B3NUNfTHpfYOClr1uHT1UgY2eblqDpJx97IAy9Bx9DUESAsPxpQl6Jb+vYRaz1w+lRNusFWPZP+qywoULHfT6iYCIYXKsvl+2tM5DnJOxoU4IYTPaMZxmKfuy+LM6iZZIzo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785426299; c=relaxed/simple; bh=cy3fDwM9nRIK8/jUxvOaoEQtEOXw0JVRmu5IzJ/pJFc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=o0Y2AXr8CJuG1RcCg4MHkvwJvxbYrVRfgp1zEf/xWcBrRky5d5ltwc1XKhfSDJ6QuHOPJANpEhqmASUe61t2/yQwwrbScjA5CXMiIxrmhm7ococbkRbylZ17haIFo9/q7018JMf6sVygwIlNWBSboqyLj0z1Yz0Eve3N338ZsOQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=doc5Es3u; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="doc5Es3u" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 779901F000E9; Thu, 30 Jul 2026 15:44:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785426298; bh=3qclgL5/tX0ch/qLDAC8/1KnA1t0QPY1s/IycrSAlrU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=doc5Es3um5252Q6FJ81l0VLxLCqr9ew+yw7pJpgNAUHkDpUii71VLqdicIQUMwO3C y/PJhGRXg5Kx4BtaNzGdAbVGvuEwOIG1/kt6a+JEiXsCarPyWY32s3JR8F4lfX2jCS YELM7/H/3s86X+1dYgM1Hm1ssX2p9ENe0EL0QKkg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+f24c3d5d316011bacc70@syzkaller.appspotmail.com, stable , Ian Abbott Subject: [PATCH 6.12 368/602] comedi: comedi_parport: deal with premature interrupt Date: Thu, 30 Jul 2026 16:12:40 +0200 Message-ID: <20260730141443.694060074@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141435.976815864@linuxfoundation.org> References: <20260730141435.976815864@linuxfoundation.org> User-Agent: quilt/0.69 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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ian Abbott commit 17221216ae8ce6a24e8a4e787382e3ebc81b88a8 upstream. Syzbot reported a general protection fault in `comedi_get_is_subdevice_running()`, which was called from the interrupt handler `parport_interrupt()` in the "comedi_parport" driver, but it does not currently have a C reproducer for the problem. It's probably due to a premature interrupt for one of two reasons: 1. The driver sets up the interrupt handler before the comedi subdevices used by the interrupt handler have been allocated, but does not disable the interrupt in the parallel port's CTRL register first. 2. The driver uses a user-supplied I/O port base address which Syzbot would have supplied, but it might not be backed by real parallel port hardware. Change the initialization order in the driver's comedi "attach" handler (`parport_attach()`) so that the hardware registers are initialized before the interrupt handler is requested. This should prevent premature interrupts occurring for real hardware. Also add a test to the interrupt handler to ensure the comedi device is fully attached and return early if it isn't. Fixes: 241ab6ad7108e ("Staging: comedi: add comedi_parport driver") Reported-by: syzbot+f24c3d5d316011bacc70@syzkaller.appspotmail.com Cc: stable Signed-off-by: Ian Abbott Link: https://patch.msgid.link/20260527125104.96596-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman --- drivers/comedi/drivers/comedi_parport.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) --- a/drivers/comedi/drivers/comedi_parport.c +++ b/drivers/comedi/drivers/comedi_parport.c @@ -211,6 +211,13 @@ static irqreturn_t parport_interrupt(int unsigned int ctrl; unsigned short val = 0; + /* + * Check device is fully attached. Device interrupts should have + * been disabled, but do this in case of bad hardware. + */ + if (!dev->attached) + return IRQ_NONE; + ctrl = inb(dev->iobase + PARPORT_CTRL_REG); if (!(ctrl & PARPORT_CTRL_IRQ_ENA)) return IRQ_NONE; @@ -231,6 +238,9 @@ static int parport_attach(struct comedi_ if (ret) return ret; + outb(0, dev->iobase + PARPORT_DATA_REG); + outb(0, dev->iobase + PARPORT_CTRL_REG); + if (it->options[1]) { ret = request_irq(it->options[1], parport_interrupt, 0, dev->board_name, dev); @@ -286,9 +296,6 @@ static int parport_attach(struct comedi_ s->cancel = parport_intr_cancel; } - outb(0, dev->iobase + PARPORT_DATA_REG); - outb(0, dev->iobase + PARPORT_CTRL_REG); - return 0; }