Re: [BUG] usb: serial: garmin_gps: A possible concurrency use-after-free bug

From: Johan Hovold
Date: Thu Dec 20 2018 - 08:46:10 EST

On Thu, Dec 20, 2018 at 09:41:16PM +0800, Jia-Ju Bai wrote:
> In drivers/usb/serial/garmin_gps.c,
> the functions garmin_read_bulk_callback() and garmin_write_bulk_callback()
> may be concurrently executed.
> In garmin_write_bulk_callback() on line 969:
> kfree(urb->transfer_buffer);
> In garmin_read_bulk_callback() on line 1165:
> unsigned char *data = urb->transfer_buffer;
> Thus, a concurrency use-after-free bug may occur.

No, they operate on different struct urb.

> This possible bug is found by a static analysis tool written by myself.

Seems you need to update your tool. Please also make sure to review its
output before reporting anything.