CVE-2026-99021 in Linux
Summary
by MITRE • 10/23/2026
In the Linux kernel, the following vulnerability has been resolved:
regulator: of: fill in supply names in of_regulator_bulk_get_all()
of_regulator_bulk_get_all() returns an array it allocated itself, and fills in only the consumer of each entry. Every other way of getting a bulk array has the supply name set, because the caller provides it, and the core expects it to be there: regulator_bulk_enable() prints it when a supply fails to enable, so a caller that hands such an array to it dereferences uninitialised memory on that path.
Copy each name into the array's own allocation, right behind the entries, so that it shares the array's lifetime and callers still have nothing extra to free. That also retires the fixed 64 byte stack buffer the names were assembled in, which is_supply_name() never bounded the copy against.
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Analysis
by VulDB Data Team • 10/23/2026
The Linux kernel regulator subsystem contains a critical memory safety flaw within the of_regulator_bulk_get_all function that results in uninitialized memory access and potential information disclosure or denial of service conditions. This vulnerability arises from an inconsistency in how supply names are handled during bulk regulator lookups compared to other similar API functions. When developers utilize standard methods for obtaining bulk regulators, they provide a buffer containing supply names which the kernel core then populates into the resulting array structure. However, the device tree specific variant of this function allocates its own internal array but fails to populate these name fields, leaving them in an undefined state rather than initializing them with null terminators or valid data strings.
The operational impact of this flaw becomes apparent when application code attempts to enable regulators using regulator_bulk_enable. This core kernel routine is designed to provide detailed diagnostic output by printing the supply names associated with each regulator entry if a specific power rail fails to activate successfully. Because the array returned by of_regulator_bulk_get_all contains uninitialized memory in its name fields, any failure path that triggers this logging mechanism will cause the kernel to dereference and read from uninitialised stack or heap memory. This constitutes an out-of-bounds read vulnerability where sensitive kernel data may be leaked to system logs or crash reports, potentially exposing internal state information to local users with access to log files.
Furthermore, the original implementation relied on a fixed sixty-four-byte buffer on the call stack to assemble these names before attempting to copy them into the array structure. The function is_supply_name lacked proper bounds checking for this copy operation, creating an additional risk of stack-based buffer overflow if input data exceeded the allocated space. By refactoring the code to allocate memory dynamically and copying each name directly behind the entries in the same allocation block, the kernel ensures that the names share the lifetime of the array itself. This approach eliminates the need for callers to manage extra free operations while simultaneously removing the dangerous fixed-size stack buffer from the execution path.
From a classification perspective, this issue aligns with CWE-908 which describes use of uninitialized resource and CWE-125 regarding out-of-bounds read vulnerabilities. The potential for information leakage through kernel log output also relates to aspects of ATT&CK technique T1074 involving data staged or collected by malware, although in this context it is an unintentional leak rather than malicious staging. Mitigation requires applying the upstream Linux kernel patch that corrects the memory initialization logic within the regulator device tree binding code. System administrators should ensure their kernels are updated to versions where of_regulator_bulk_get_all properly initializes all structure members and utilizes dynamic allocation for name storage, thereby preventing both information disclosure via log dumps and potential stack corruption from unbounded copy operations.