linux-kernel - Re: [PATCH v2] usb: Fix null-ptr-deref in qt2_process_read

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Message-ID: <Z4VXcZLcFxA8AQ-b@qasdev.system>
Date: Mon, 13 Jan 2025 18:12:01 +0000
From: Qasim Ijaz <qasdev00@...il.com>
To: Johan Hovold <johan@...nel.org>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v2] usb: Fix null-ptr-deref in qt2_process_read_urb()

On Mon, Jan 13, 2025 at 10:00:18AM +0100, Johan Hovold wrote:
> On Sun, Jan 12, 2025 at 09:55:58AM +0000, Qasim Ijaz wrote:
> > This patch addresses a null-ptr-deref in qt2_process_read_urb() due to
> > an incorrect bounds check in the following:
> 
> Thanks for the fix. This looks correct, but your patch is whitespace
> damaged (tabs replaced with spaces) and does not apply.
> 
> Can you please fix your mail setup and resend a v3? (Make sure to send
> it to yourself first.)
> 
> When doing so, please use the common patch prefix for this driver:
> 
> 	USB: serial: quatech2:
> 
> > ""
> 
> You can drop these (markup?) quotes.
> 
> >        if (newport > serial->num_ports) {
> >                dev_err(&port->dev,
> >                        "%s - port change to invalid port: %i\n",
> >                        __func__, newport);
> >                break;
> >        }
> > ""
> > 
> > The condition doesn't account for the valid range of the serial->port
> > buffer, which is from 0 to serial->num_ports - 1. When newport is equal
> > to serial->num_ports, the assignment of "port" in the
> > following code is out-of-bounds and NULL:
> > 
> > ""
> >        serial_priv->current_port = newport;
> >        port = serial->port[serial_priv->current_port];
> > 
> > ""
> > 
> > The fix checks if newport is greater than or equal to serial->num_ports
> > indicating it is out-of-bounds.
> > 
> > Reported-by: syzbot <syzbot+506479ebf12fe435d01a@...kaller.appspotmail.com>
> > Closes: https://syzkaller.appspot.com/bug?extid=506479ebf12fe435d01a
> > Signed-off-by: Qasim Ijaz <qasdev00@...il.com>
> 
> And please include a Fixes and CC stable tag:
> 
> 	Fixes: f7a33e608d9a ("USB: serial: add quatech2 usb to serial driver")
> 	Cc: stable@...r.kernel.org	# 3.5
> 
> Johan

Hi Johan,

Thank you for your feedback on the previous version. I've sent the v3 patch addressing the issues: fixed whitespace damage, removed quotes, updated the prefix, and added Fixes and Cc tags.

Best regards,
Qasim