CVE-2026-99259 in Linux
Summary
by MITRE • 11/03/2026
In the Linux kernel, the following vulnerability has been resolved:
soc/tegra: pmc: Fix uninitialised clock rate
For legacy 32-bit Tegra devices, the warning in the tegra_pmc_enter_suspend_mode() function is being triggered because the early_pmc->rate variable is never configured and hence, always 0. This issue started occurring after updating the PMC driver to create the PMC context dynamically which causes the 'rate' to be set in the new dynamic context, but missed updating the rate in the early PMC context.
Fix this by initialising the early_pmc->rate variable for 32-bit Tegra devices when the rate for the PMC context is initialised.
[[email protected]: move assignment to existing #ifdef block]
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Analysis
by VulDB Data Team • 11/03/2026
The Linux kernel vulnerability identified in the NVIDIA Tegra System on Chip power management controller driver represents a classic instance of improper initialization leading to undefined behavior during system suspend operations. This issue specifically affects legacy 32-bit Tegra devices and stems from an architectural change within the PMC driver where the context for managing power states was transitioned from static allocation to dynamic creation. While this refactoring successfully ensured that the rate variable in the newly allocated dynamic context is properly configured, it inadvertently left the early_pmc structure uninitialized regarding its clock rate field. Consequently, when the system attempts to enter suspend mode via the tegra_pmc_enter_suspend_mode function, the code relies on a value that has never been assigned, resulting in an always-zero state for this critical parameter.
From a technical perspective, the core flaw lies in the failure to synchronize initialization logic across different structural contexts within the driver. The early PMC context is utilized during specific phases of system boot and power management transitions where timing precision is paramount. By neglecting to set the rate variable in this legacy structure when initializing the broader PMC context, the kernel introduces a latent defect that manifests as operational warnings or potential instability during low-power state entry. This type of error falls squarely under CWE-457, which defines an uninitialised local variable, and can lead to unpredictable system behavior depending on how subsequent logic interprets this zero value in timing calculations or hardware register configurations.
The operational impact of this vulnerability is primarily observed through the triggering of kernel warnings during suspend sequences, which indicates a deviation from expected driver state management protocols. Although immediate catastrophic failure may not always occur due to defensive coding practices elsewhere in the power management subsystem, such anomalies can lead to increased latency in entering low-power states or potential hardware misconfiguration if the zero rate is used for clock gating decisions without proper validation checks. Over time, repeated occurrences of these warnings can clutter system logs and obscure more critical issues, while also posing a risk to device reliability by potentially preventing optimal power savings or causing unexpected wake-ups due to incorrect timing parameters.
To mitigate this vulnerability, developers must ensure that the early_pmc->rate variable is explicitly initialized for 32-bit Tegra devices at the same point where the PMC context rate is established. This involves modifying the driver code to include an assignment statement within the existing conditional compilation block dedicated to legacy hardware support. By aligning the initialization of the early context with the dynamic context, consistency is restored across all execution paths that interact with the power management controller. Maintaining strict parity between static and dynamic resource initialization in kernel drivers is essential for preventing such discrepancies, especially when refactoring complex subsystems like those found in SoC architectures where multiple contexts may share underlying hardware resources but require distinct configuration states.