This is a note to let you know that I've just added the patch titled

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

to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-next branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release during the merge window.

If you have any questions about this process, please let me know.

From 575a5adf48b06a2980c9eeffedf699ed5534fade Mon Sep 17 00:00:00 2001 From: Qasim Ijaz qasdev00@gmail.com Date: Mon, 13 Jan 2025 18:00:34 +0000 Subject: 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: 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 --- drivers/usb/serial/quatech2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/serial/quatech2.c b/drivers/usb/serial/quatech2.c index a317bdbd00ad..72fe83a6c978 100644 --- a/drivers/usb/serial/quatech2.c +++ b/drivers/usb/serial/quatech2.c @@ -503,7 +503,7 @@ static void qt2_process_read_urb(struct urb *urb)

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);