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USB: serial: quatech2: fix null-ptr-deref in qt2_process_read_urb() 

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@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=506479ebf12fe435d01a
Fixes: f7a33e608d ("USB: serial: add quatech2 usb to serial driver")
Cc: <stable@vger.kernel.org>      # 3.5
Signed-off-by: Qasim Ijaz <qasdev00@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
This commit is contained in:
Qasim Ijaz 2025-01-13 18:00:34 +00:00 committed by Johan Hovold
parent 138a99ca4e
commit 575a5adf48
1 changed files with 1 additions and 1 deletions
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2
drivers/usb/serial/quatech2.c
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@ -503,7 +503,7 @@ static void qt2_process_read_urb(struct urb *urb)
newport = *(ch + 3); newport = *(ch + 3);
if (newport > serial->num_ports) { if (newport >= serial->num_ports) {
dev_err(&port->dev, dev_err(&port->dev,
"%s - port change to invalid port: %i\n", "%s - port change to invalid port: %i\n",
__func__, newport); __func__, newport);