CVE-2022-48867 Information

Description

In the Linux kernel the following vulnerability has been resolved:

dmaengine: idxd: Prevent use after free on completion memory

On driver unload any pending descriptors are flushed at the time the interrupt is freed: idxd_dmaengine_drv_remove() -> drv_disable_wq() -> idxd_wq_free_irq() -> idxd_flush_pending_descs().

If there are any descriptors present that need to be flushed this flow triggers a ot present\ page fault as below:

BUG: unable to handle page fault for address: ff391c97c70c9040 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page

The address that triggers the fault is the address of the descriptor that was freed moments earlier via: drv_disable_wq()->idxd_wq_free_resources()

Fix the use after free by freeing the descriptors after any possible usage. This is done after idxd_wq_reset() to ensure that the memory remains accessible during possible completion writes by the device.

Reference

https://git.kernel.org/stable/c/b9e8e3fcfec625fc1c2f68f684448aeeb882625b https://git.kernel.org/stable/c/1beeec45f9ac31eba52478379f70a5fa9c2ad005