5.4-stable review patch. If anyone has any objections, please let me know.
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From: Qasim Ijaz qasdev00@gmail.com
commit 575a5adf48b06a2980c9eeffedf699ed5534fade upstream.
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: f7a33e608d9a ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/serial/quatech2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/usb/serial/quatech2.c +++ b/drivers/usb/serial/quatech2.c @@ -555,7 +555,7 @@ static void qt2_process_read_urb(struct
newport = *(ch + 3);
- if (newport > serial->num_ports) { + if (newport >= serial->num_ports) { dev_err(&port->dev, "%s - port change to invalid port: %i\n", __func__, newport);