CVE-2023-33110 in 4 Gen 1 Mobile Platform
Summary
by MITRE • 01/02/2024
The session index variable in PCM host voice audio driver initialized before PCM open, accessed during event callback from ADSP and reset during PCM close may lead to race condition between event callback - PCM close and reset session index causing memory corruption.
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Analysis
by VulDB Data Team • 01/22/2024
The vulnerability described in CVE-2023-33110 represents a critical race condition within the PCM host voice audio driver component of embedded audio systems. This flaw manifests when the session index variable undergoes improper initialization timing relative to PCM open operations, creating a scenario where the variable is accessed during asynchronous event callbacks originating from the ADSP (Audio Digital Signal Processor). The timing discrepancy between variable initialization, callback execution, and resource cleanup creates a window where concurrent operations can corrupt memory structures. The session index variable is initialized before the PCM open function completes, yet it is accessed during event callbacks that may occur while the PCM subsystem is actively processing audio data. During PCM close operations, the session index variable undergoes reset operations that can conflict with ongoing event callback processing, leading to unpredictable memory access patterns and potential corruption of critical audio processing data structures.
This race condition directly impacts the stability and security of audio processing subsystems within embedded devices, particularly those utilizing advanced audio processing architectures. The vulnerability stems from improper synchronization mechanisms between different execution contexts within the audio driver, where the event callback thread and the PCM close thread operate without adequate mutual exclusion controls. The session index variable serves as a critical synchronization primitive that tracks active audio sessions, and its improper handling creates opportunities for memory corruption that could be exploited to disrupt audio services or potentially escalate privileges within the audio subsystem. The timing aspects of this vulnerability align with common race condition patterns identified in CWE-362, which specifically addresses concurrent execution timing issues, and CWE-367, which covers time-of-check to time-of-use flaws that can occur when resource state changes between validation and usage operations.
The operational impact of this vulnerability extends beyond simple audio disruption to potentially compromise the entire audio processing pipeline and underlying system stability. Memory corruption resulting from the race condition can lead to system crashes, audio artifacts, or complete audio subsystem failure that may require system reboot to recover. In embedded systems where audio processing is critical for device functionality, this vulnerability could result in complete device unavailability or degraded performance during audio operations. The asynchronous nature of event callbacks from ADSP components makes this vulnerability particularly challenging to detect and reproduce in testing environments, as it depends on precise timing conditions between multiple concurrent threads. Attackers could potentially exploit this race condition to cause denial of service attacks against audio services or to gain unauthorized access to audio processing resources through memory corruption techniques.
Mitigation strategies for CVE-2023-33110 must address the fundamental synchronization issues within the PCM host voice audio driver. The primary solution involves implementing proper mutual exclusion mechanisms such as mutex locks or semaphores around access to the session index variable during event callback processing and PCM close operations. The initialization timing of the session index variable should be carefully coordinated with PCM open completion to ensure proper state management throughout the audio processing lifecycle. Additionally, defensive programming techniques including proper resource cleanup procedures and validation checks should be implemented to prevent use-after-free or double-free conditions that can occur when the session index variable is reset during PCM close operations. Systematic code review and static analysis should be conducted to identify similar race condition patterns within the audio driver codebase, particularly focusing on variables that undergo initialization, access, and reset operations in concurrent execution contexts. The implementation of proper locking mechanisms aligns with ATT&CK technique T1070.004 which covers "File and Directory Permissions Modification" and T1547.001 which addresses "Registry Run Keys / Startup Folder" in the context of maintaining system stability and preventing unauthorized access to critical system resources.