CVE-2022-49350

Summary

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)

Affected Software

VendorProductVersion RangeStatus
LinuxLinux90eff9096c01ba90cdae504a6b95ee87fe2556a3 < ab64ec2c75683f30ccde9eaaf0761002f901aa12affected
LinuxLinux90eff9096c01ba90cdae504a6b95ee87fe2556a3 < 5534bcd7c40299862237c4a8fd9c5031b3db1538affected
LinuxLinux90eff9096c01ba90cdae504a6b95ee87fe2556a3 < 6a90a44d53428a3bf01bd80df9ba78b19959270caffected
LinuxLinux90eff9096c01ba90cdae504a6b95ee87fe2556a3 < 7759c3222815b945a94b212bc0c6cdec475cfec2affected
LinuxLinux90eff9096c01ba90cdae504a6b95ee87fe2556a3 < 59fa94cddf9eef8d8dae587373eed8b8f4eb11d7affected
LinuxLinux90eff9096c01ba90cdae504a6b95ee87fe2556a3 < f5c68137f1191ba3fcf6260ec71b30be2e2bf4c3affected
LinuxLinux90eff9096c01ba90cdae504a6b95ee87fe2556a3 < f2f0f8c18b60ca64ff50892ed899cf1c77864755affected
LinuxLinux90eff9096c01ba90cdae504a6b95ee87fe2556a3 < 35b42dce619701f1300fb8498dae82c9bb1f0263affected
LinuxLinux4.12affected
LinuxLinux0 < 4.12unaffected
LinuxLinux4.14.283 <= 4.14.*unaffected
LinuxLinux4.19.247 <= 4.19.*unaffected
LinuxLinux5.4.198 <= 5.4.*unaffected
LinuxLinux5.10.122 <= 5.10.*unaffected
LinuxLinux5.15.47 <= 5.15.*unaffected
LinuxLinux5.17.15 <= 5.17.*unaffected
LinuxLinux5.18.4 <= 5.18.*unaffected
LinuxLinux5.19 <= *unaffected

Weaknesses

References