Re: [PATCH] usb: Fix null-ptr-deref in qt2_process_read_urb()

[Greg Kroah-Hartman]

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@xxxxxxxxxxxxxxxxxxxxxxxxx>
> Closes: https://syzkaller.appspot.com/bug?extid=506479ebf12fe435d01a
> Tested-by: syzbot <syzbot+506479ebf12fe435d01a@xxxxxxxxxxxxxxxxxxxxxxxxx>
> Tested-by: Qasim Ijaz <qasdev00@xxxxxxxxx>
> Signed-off-by: Qasim Ijaz <qasdev00@xxxxxxxxx>

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