CVE-2024-35978 in Linux
Summary
by MITRE • 05/20/2024
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: Fix memory leak in hci_req_sync_complete()
In 'hci_req_sync_complete()', always free the previous sync request state before assigning reference to a new one.
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Analysis
by VulDB Data Team • 02/12/2025
The vulnerability identified as CVE-2024-35978 represents a critical memory management flaw within the Linux kernel's Bluetooth subsystem that specifically affects the hci_req_sync_complete() function. This issue resides in the Bluetooth HCI (Host Controller Interface) layer which serves as the primary communication interface between the host system and Bluetooth controllers. The flaw manifests as a memory leak that occurs during the synchronization of Bluetooth requests, where the kernel fails to properly release previously allocated memory resources before establishing new references. Such memory management deficiencies are particularly dangerous in kernel space operations as they can lead to progressive resource exhaustion and system instability. The vulnerability impacts all Linux kernel versions that incorporate the affected Bluetooth HCI implementation, making it a widespread concern for systems utilizing Bluetooth connectivity.
The technical root cause of this vulnerability stems from improper memory deallocation practices within the hci_req_sync_complete() function. When processing Bluetooth synchronization requests, the kernel maintains state information for previous operations that must be properly cleaned up before new state data is assigned. The flaw occurs because the function does not consistently execute the memory deallocation routine for the prior synchronization request state before assigning a reference to a new one. This creates a situation where memory allocated for previous request states remains allocated indefinitely, leading to gradual memory consumption that can eventually exhaust available system resources. The issue is classified as a memory leak under CWE-401 and represents a classic example of improper resource management in kernel space code. The vulnerability operates at the kernel level where memory management operations are critical for system stability and performance.
The operational impact of this memory leak vulnerability extends beyond simple resource consumption to potentially compromise system availability and overall performance. As the memory leak accumulates over time, it can lead to memory pressure that affects other system processes and services. In high-traffic Bluetooth environments or systems with continuous Bluetooth operations, the leak may manifest more rapidly, potentially causing system slowdowns, application crashes, or in severe cases, complete system hangs. The vulnerability is particularly concerning for embedded systems, servers, and devices that rely heavily on Bluetooth connectivity and continuous operation. Attackers could potentially exploit this vulnerability by forcing repeated Bluetooth synchronization operations to accelerate memory exhaustion, leading to denial of service conditions that align with ATT&CK technique T1499.200 for resource exhaustion attacks. The persistent nature of memory leaks makes this vulnerability especially dangerous in long-running systems where the cumulative effect of the leak becomes increasingly problematic.
Mitigation strategies for CVE-2024-35978 focus on implementing proper memory management practices within the kernel Bluetooth subsystem. The primary fix involves ensuring that hci_req_sync_complete() always executes memory deallocation for previous synchronization request states before assigning new references. This requires careful code review and modification to guarantee that all memory allocation paths properly account for cleanup operations. System administrators should prioritize applying the kernel patches that address this vulnerability, particularly in environments where Bluetooth connectivity is actively used. Monitoring for memory usage patterns and implementing automated alerting for unusual memory consumption trends can help detect exploitation attempts. Additionally, organizations should consider implementing Bluetooth access controls and limiting unnecessary Bluetooth operations to reduce exposure risk. The fix aligns with security best practices for kernel memory management and represents a standard remediation approach for similar memory leak vulnerabilities in operating system components.