Bug 2468179 (CVE-2026-43401)

Summary: CVE-2026-43401 kernel: cpufreq: intel_pstate: Fix NULL pointer dereference in update_cpu_qos_request()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Linux kernel's `intel_pstate` component. This vulnerability arises when the system is booted with the "nosmt" parameter, causing a critical error known as a null pointer dereference in the `update_cpu_qos_request()` function. Such an error can lead to system instability and potentially a kernel crash, effectively causing a denial of service (DoS) for the affected system.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-05-08 15:03:16 UTC 
In the Linux kernel, the following vulnerability has been resolved:

cpufreq: intel_pstate: Fix NULL pointer dereference in update_cpu_qos_request()

The update_cpu_qos_request() function attempts to initialize the 'freq'
variable by dereferencing 'cpudata' before verifying if the 'policy'
is valid.

This issue occurs on systems booted with the "nosmt" parameter, where
all_cpu_data[cpu] is NULL for the SMT sibling threads. As a result,
any call to update_qos_requests() will result in a NULL pointer
dereference as the code will attempt to access pstate.turbo_freq using
the NULL cpudata pointer.

Also, pstate.turbo_freq may be updated by intel_pstate_get_hwp_cap()
after initializing the 'freq' variable, so it is better to defer the
'freq' until intel_pstate_get_hwp_cap() has been called.

Fix this by deferring the 'freq' assignment until after the policy and
driver_data have been validated.

[ rjw: Added one paragraph to the changelog ]
Comment 1 Keith Grant 2026-05-08 22:06:21 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050840-CVE-2026-43401-c331@gregkh/T