# CVE-2021-47229: linux: In the Linux kernel, the following vulnerability has been resolved:  PCI: aardvark: Fix kernel panic during PIO trans...

CVE-2021-47229 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47229, released May 21, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-47229
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0023
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 21, 2024

## 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 other errors to kernel and instead throw panic from EL3 Trusted Firmware handler.  Links to discussion and patches about this issue: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/commit/?id=3c7dcdac5c50 https://lore.kernel.org/linux-pci/20190316161243.29517-1-repk@triplefau.lt/ https://lore.kernel.org/linux-pci/971be151d24312cc533989a64bd454b4@www.loen.fr/ https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/1541  But the real cause was the fact that during link retraining or after link down event the PIO transfer may take longer time, up to the 1.44s until it times out. This increased probability that a new PIO transfer would be issued by kernel while previous one has not finished yet.  After applying this change into the kernel, it is possible to revert the mentioned TF-A hack and SError events do not have to be caught in TF-A EL3.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.10.46-1 | [DEBIAN-CVE-2021-47229](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47229.md) | May 21, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.10.46-1 | [DEBIAN-CVE-2021-47229](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47229.md) | May 21, 2024 |
| Linux | linux Debian 14 | 5.10.46-1 | [DEBIAN-CVE-2021-47229](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47229.md) | May 21, 2024 |

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