In the Linux kernel, the following vulnerability has been resolved: serial: 8250: omap: Don't skip resource freeing if pm_runtime_resume_and_get() failed Returning an error code from .remove() makes the driver core emit the little helpful error message: remove callback returned a non-zero value. This will be ignored. and then remove the device anyhow. So all resources that were not freed are leaked in this case. Skipping serial8250_unregister_port() has the potential to keep enough of the UART around to trigger a use-after-free. So replace the error return (and with it the little helpful error message) by a more useful error message and continue to cleanup.
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.