CVE-2024-49955 in Linux
Summary
by MITRE • 10/21/2024
In the Linux kernel, the following vulnerability has been resolved:
ACPI: battery: Fix possible crash when unregistering a battery hook
When a battery hook returns an error when adding a new battery, then the battery hook is automatically unregistered. However the battery hook provider cannot know that, so it will later call battery_hook_unregister() on the already unregistered battery hook, resulting in a crash.
Fix this by using the list head to mark already unregistered battery hooks as already being unregistered so that they can be ignored by battery_hook_unregister().
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Analysis
by VulDB Data Team • 03/21/2026
The vulnerability described in CVE-2024-49955 represents a critical race condition and memory management flaw within the Linux kernel's ACPI battery subsystem. This issue specifically affects the battery hook registration and unregistration mechanism that handles power management events for battery devices. The vulnerability stems from improper state tracking within the kernel's battery hook management system, creating a scenario where a double-free or use-after-free condition can occur during the cleanup phase of battery hook operations.
The technical flaw manifests when a battery hook encounters an error during the registration process, causing the kernel to automatically unregister the hook. However, the original battery hook provider maintains no awareness of this automatic unregistration event. Subsequently, when the provider attempts to manually unregister the same hook through battery_hook_unregister(), it operates on a structure that has already been freed from the system's active list. This fundamental race condition between automatic and manual cleanup operations results in undefined behavior and ultimately a kernel crash, as the system attempts to access memory that has already been deallocated.
The operational impact of this vulnerability extends beyond simple system instability, as it represents a potential denial of service vector that could affect laptop and mobile device power management capabilities. When a battery hook fails to register properly due to hardware or driver issues, the automatic unregistration process combined with the subsequent manual cleanup attempt creates a crash loop that could render the device's power management subsystem non-functional. This affects systems running Linux kernels that implement ACPI battery management, particularly those with complex power management requirements where battery hooks are frequently used to handle device-specific power events and notifications.
The fix for this vulnerability addresses the core issue by implementing proper state tracking through the list head mechanism that marks battery hooks as already unregistered. This approach prevents the duplicate unregistration attempt by checking the registration status before proceeding with cleanup operations. The solution aligns with standard kernel development practices for managing concurrent access to shared data structures and demonstrates proper resource state management. This remediation follows established patterns for preventing double-free conditions and memory corruption issues that are commonly classified under CWE-415 and CWE-416, which address improper cleanup and use-after-free vulnerabilities respectively.
Security implications of this vulnerability extend to potential exploitation scenarios where an attacker could craft malicious battery hook providers to trigger the crash condition repeatedly, leading to system instability or denial of service. The fix ensures that the kernel's power management subsystem maintains consistent state information and prevents arbitrary code execution through memory corruption. This vulnerability highlights the importance of proper synchronization and state management in kernel space operations, particularly in subsystems that handle critical system resources like power management components. The resolution provides a robust mechanism for tracking battery hook lifecycle states, preventing both the automatic and manual cleanup operations from interfering with each other and maintaining system stability during battery management operations. The solution adheres to the principle of defensive programming and proper resource management that aligns with the ATT&CK framework's system binary exploitation and privilege escalation categories, ensuring that kernel-level resources remain properly managed and accessible only through legitimate system pathways.