Bug 2391072 (CVE-2025-38521)

Summary: CVE-2025-38521 kernel: Linux kernel: Denial of Service in drm/imagination driver via improper GPU reset handling
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in the Linux kernel's `drm/imagination` driver. A local user with low privileges could trigger a kernel crash by initiating a GPU hard reset. This occurs because the power management functions `pm_runtime_force_suspend()` and `pm_runtime_force_resume()` are improperly used, preventing the GPU clocks from being re-enabled. This vulnerability leads to a Denial of Service (DoS) on the affected system.
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Description OSIDB Bzimport 2025-08-26 15:10:12 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/imagination: Fix kernel crash when hard resetting the GPU

The GPU hard reset sequence calls pm_runtime_force_suspend() and
pm_runtime_force_resume(), which according to their documentation should
only be used during system-wide PM transitions to sleep states.

The main issue though is that depending on some internal runtime PM
state as seen by pm_runtime_force_suspend() (whether the usage count is
<= 1), pm_runtime_force_resume() might not resume the device unless
needed. If that happens, the runtime PM resume callback
pvr_power_device_resume() is not called, the GPU clocks are not
re-enabled, and the kernel crashes on the next attempt to access GPU
registers as part of the power-on sequence.

Replace calls to pm_runtime_force_suspend() and
pm_runtime_force_resume() with direct calls to the driver's runtime PM
callbacks, pvr_power_device_suspend() and pvr_power_device_resume(),
to ensure clocks are re-enabled and avoid the kernel crash.
Comment 1 Jon Moroney 2025-08-26 15:39:45 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025081654-CVE-2025-38521-4543@gregkh/T