CVE-2021-47229

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

PCI: aardvark: Fix kernel panic during PIO transfer

Trying to start a new PIO transfer by writing value 0 in PIO_START register

when previous transfer has not yet completed (which is indicated by value 1

in PIO_START) causes an External Abort on CPU, which results in kernel

panic:

SError Interrupt on CPU0, code 0xbf000002 -- SError

Kernel panic - not syncing: Asynchronous SError Interrupt

To prevent kernel panic, it is required to reject a new PIO transfer when

previous one has not finished yet.

If previous PIO transfer is not finished yet, the kernel may issue a new

PIO request only if the previous PIO transfer timed out.

In the past the root cause of this issue was incorrectly identified (as it

often happens during link retraining or after link down event) and special

hack was implemented in Trusted Firmware to catch all SError events in EL3,

to ignore errors with code 0xbf000002 and not forwarding any

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References