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

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Message-ID: <Z4OV7184kahqhzBl@qasdev.system>
Date: Sun, 12 Jan 2025 10:14:07 +0000
From: Qasim Ijaz <qasdev00@...il.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: Fix null-ptr-deref in qt2_process_read_urb()

On Sun, Jan 12, 2025 at 09:42:45AM +0100, Greg Kroah-Hartman wrote:
> On Sat, Jan 11, 2025 at 08:08:49PM +0000, qasdev wrote:
> > This patch addresses a null-ptr-deref in qt2_process_read_urb() due to
> > an incorrect bounds check in the following:
> > 
> > ""
> >        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
> > Tested-by: syzbot <syzbot+506479ebf12fe435d01a@...kaller.appspotmail.com>
> > Tested-by: Qasim Ijaz <qasdev00@...il.com>
> > Signed-off-by: Qasim Ijaz <qasdev00@...il.com>
> 
> Your signed-off-by does not match your "From:" line :(
> 
> Also, no need to add a tested-by when you sign off on your own patch,
> that is usually implied.
> 
> thanks,
> 
> greg k-h

Hi Greg,

Thank you for your feedback on my patch. I’ve sent a v2 patch in a new thread, addressing the issues with the From: line and removing the redundant Tested-by tag.

Best regards,
Qasim