Bug 2492429 (CVE-2026-53042)

Summary: CVE-2026-53042 kernel: fwctl: Fix class init ordering to avoid NULL pointer dereference on device removal
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's `fwctl` module. An issue with the class initialization ordering can lead to a null pointer dereference when a device is removed. This can cause a system crash, resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-06-24 18:11:35 UTC 
In the Linux kernel, the following vulnerability has been resolved:

fwctl: Fix class init ordering to avoid NULL pointer dereference on device removal

CXL is linked before fwctl in drivers/Makefile. Both use `module_init, so
`cxl_pci_driver_init()` runs first. When `cxl_pci_probe()` calls
`fwctl_register()` and then `device_add()`, fwctl_class is not yet
registered because fwctl_init() hasn't run, causing `class_to_subsys()` to
return NULL and skip knode_class initialization.

On device removal, `class_to_subsys()` returns non-NULL, and
`device_del()` calls `klist_del()` on the uninitialized knode, triggering
a NULL pointer dereference.
Comment 1 Mauro Matteo Cascella 2026-06-26 11:36:53 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062457-CVE-2026-53042-9758@gregkh/T