# CVE-2021-47439: linux: In the Linux kernel, the following vulnerability has been resolved:  net: dsa: microchip: Added the condition for sch...

CVE-2021-47439 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47439, released May 22, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-47439
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0023
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 22, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  net: dsa: microchip: Added the condition for scheduling ksz_mib_read_work  When the ksz module is installed and removed using rmmod, kernel crashes with null pointer dereferrence error. During rmmod, ksz_switch_remove function tries to cancel the mib_read_workqueue using cancel_delayed_work_sync routine and unregister switch from dsa.  During dsa_unregister_switch it calls ksz_mac_link_down, which in turn reschedules the workqueue since mib_interval is non-zero. Due to which queue executed after mib_interval and it tries to access dp->slave. But the slave is unregistered in the ksz_switch_remove function. Hence kernel crashes.  To avoid this crash, before canceling the workqueue, resetted the mib_interval to 0.  v1 -> v2: -Removed the if condition in ksz_mib_read_work

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.14.16-1 | [DEBIAN-CVE-2021-47439](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47439.md) | May 22, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.14.16-1 | [DEBIAN-CVE-2021-47439](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47439.md) | May 22, 2024 |
| Linux | linux Debian 14 | 5.14.16-1 | [DEBIAN-CVE-2021-47439](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47439.md) | May 22, 2024 |

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