# CVE-2022-48818: linux: In the Linux kernel, the following vulnerability has been resolved:  net: dsa: mv88e6xxx: don't use devres for mdiobu...

CVE-2022-48818 is fixed in linux on 1 platform, first by DEBIAN-CVE-2022-48818, released July 16, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-48818
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0028
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 16, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  net: dsa: mv88e6xxx: don't use devres for mdiobus  As explained in commits: 74b6d7d13307 ("net: dsa: realtek: register the MDIO bus under devres") 5135e96a3dd2 ("net: dsa: don't allocate the slave_mii_bus using devres")  mdiobus_free() will panic when called from devm_mdiobus_free() <- devres_release_all() <- __device_release_driver(), and that mdiobus was not previously unregistered.  The mv88e6xxx is an MDIO device, so the initial set of constraints that I thought would cause this (I2C or SPI buses which call ->remove on ->shutdown) do not apply. But there is one more which applies here.  If the DSA master itself is on a bus that calls ->remove from ->shutdown (like dpaa2-eth, which is on the fsl-mc bus), there is a device link between the switch and the DSA master, and device_links_unbind_consumers() will unbind the Marvell switch driver on shutdown.  systemd-shutdown[1]: Powering off. mv88e6085 0x0000000008b96000:00 sw_gl0: Link is Down fsl-mc dpbp.9: Removing from iommu group 7 fsl-mc dpbp.8: Removing from iommu group 7 ------------[ cut here ]------------ kernel BUG at drivers/net/phy/mdio_bus.c:677! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 1 Comm: systemd-shutdow Not tainted 5.16.5-00040-gdc05f73788e5 #15 pc : mdiobus_free+0x44/0x50 lr : devm_mdiobus_free+0x10/0x20 Call trace:  mdiobus_free+0x44/0x50  devm_mdiobus_free+0x10/0x20  devres_release_all+0xa0/0x100  __device_release_driver+0x190/0x220  device_release_driver_internal+0xac/0xb0  device_links_unbind_consumers+0xd4/0x100  __device_release_driver+0x4c/0x220  device_release_driver_internal+0xac/0xb0  device_links_unbind_consumers+0xd4/0x100  __device_release_driver+0x94/0x220  device_release_driver+0x28/0x40  bus_remove_device+0x118/0x124  device_del+0x174/0x420  fsl_mc_device_remove+0x24/0x40  __fsl_mc_device_remove+0xc/0x20  device_for_each_child+0x58/0xa0  dprc_remove+0x90/0xb0  fsl_mc_driver_remove+0x20/0x5c  __device_release_driver+0x21c/0x220  device_release_driver+0x28/0x40  bus_remove_device+0x118/0x124  device_del+0x174/0x420  fsl_mc_bus_remove+0x80/0x100  fsl_mc_bus_shutdown+0xc/0x1c  platform_shutdown+0x20/0x30  device_shutdown+0x154/0x330  kernel_power_off+0x34/0x6c  __do_sys_reboot+0x15c/0x250  __arm64_sys_reboot+0x20/0x30  invoke_syscall.constprop.0+0x4c/0xe0  do_el0_svc+0x4c/0x150  el0_svc+0x24/0xb0  el0t_64_sync_handler+0xa8/0xb0  el0t_64_sync+0x178/0x17c  So the same treatment must be applied to all DSA switch drivers, which is: either use devres for both the mdiobus allocation and registration, or don't use devres at all.  The Marvell driver already has a good structure for mdiobus removal, so just plug in mdiobus_free and get rid of devres.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.16.10-1 | [DEBIAN-CVE-2022-48818](https://patchblox.com/security/data/fix/linux/debian-cve-2022-48818.md) | Jul 16, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.16.10-1 | [DEBIAN-CVE-2022-48818](https://patchblox.com/security/data/fix/linux/debian-cve-2022-48818.md) | Jul 16, 2024 |
| Linux | linux Debian 14 | 5.16.10-1 | [DEBIAN-CVE-2022-48818](https://patchblox.com/security/data/fix/linux/debian-cve-2022-48818.md) | Jul 16, 2024 |

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