Bug 2320664 (CVE-2022-49016)

Summary: CVE-2022-49016 kernel: net: mdiobus: fix unbalanced node reference count
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A vulnerability was found in the Linux kernel's mdiobus subsystem, causing unbalanced reference counts for firmware nodes (fwnode), leading to memory leaks and potential instability. The issue occurred because fwnode_mdiobus_phy_device_register() incremented the reference count for non-ACPI nodes without a corresponding decrement during device release, while the ACPI nodes lacked proper reference balancing in error paths.
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Description OSIDB Bzimport 2024-10-21 21:01:26 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net: mdiobus: fix unbalanced node reference count

I got the following report while doing device(mscc-miim) load test
with CONFIG_OF_UNITTEST and CONFIG_OF_DYNAMIC enabled:

  OF: ERROR: memory leak, expected refcount 1 instead of 2,
  of_node_get()/of_node_put() unbalanced - destroy cset entry:
  attach overlay node /spi/soc@0/mdio@7107009c/ethernet-phy@0

If the 'fwnode' is not an acpi node, the refcount is get in
fwnode_mdiobus_phy_device_register(), but it has never been
put when the device is freed in the normal path. So call
fwnode_handle_put() in phy_device_release() to avoid leak.

If it's an acpi node, it has never been get, but it's put
in the error path, so call fwnode_handle_get() before
phy_device_register() to keep get/put operation balanced.
Comment 1 Avinash Hanwate 2024-10-22 09:05:52 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024102153-CVE-2022-49016-c7bb@gregkh/T