Bug 2348007 (CVE-2022-49350)

Summary: CVE-2022-49350 kernel: net: mdio: unexport __init-annotated mdio_bus_init()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: low    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2025-02-26 03:14:22 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net: mdio: unexport __init-annotated mdio_bus_init()

EXPORT_SYMBOL and __init is a bad combination because the .init.text
section is freed up after the initialization. Hence, modules cannot
use symbols annotated __init. The access to a freed symbol may end up
with kernel panic.

modpost used to detect it, but it has been broken for a decade.

Recently, I fixed modpost so it started to warn it again, then this
showed up in linux-next builds.

There are two ways to fix it:

  - Remove __init
  - Remove EXPORT_SYMBOL

I chose the latter for this case because the only in-tree call-site,
drivers/net/phy/phy_device.c is never compiled as modular.
(CONFIG_PHYLIB is boolean)
Comment 3 Avinash Hanwate 2025-02-27 21:54:38 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025022642-CVE-2022-49350-c5d2@gregkh/T