CVE-2023-52736 in Linux
Summary
by MITRE • 05/21/2024
In the Linux kernel, the following vulnerability has been resolved:
ALSA: hda: Do not unset preset when cleaning up codec
Several functions that take part in codec's initialization and removal are re-used by ASoC codec drivers implementations. Drivers mimic the behavior of hda_codec_driver_probe/remove() found in sound/pci/hda/hda_bind.c with their component->probe/remove() instead.
One of the reasons for that is the expectation of snd_hda_codec_device_new() to receive a valid pointer to an instance of struct snd_card. This expectation can be met only once sound card components probing commences.
As ASoC sound card may be unbound without codec device being actually removed from the system, unsetting ->preset in snd_hda_codec_cleanup_for_unbind() interferes with module unload -> load scenario causing null-ptr-deref. Preset is assigned only once, during device/driver matching whereas ASoC codec driver's module reloading may occur several times throughout the lifetime of an audio stack.
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Analysis
by VulDB Data Team • 09/23/2025
The vulnerability CVE-2023-52736 represents a critical issue within the Linux kernel's Advanced Sound Architecture implementation, specifically affecting the HDA (High Definition Audio) codec handling mechanisms. This flaw manifests in the ALSA subsystem where the kernel's audio driver framework fails to properly manage codec preset states during device unbinding operations, creating potential for null pointer dereferences that could lead to system instability or crashes. The issue stems from the complex interaction between traditional PCI-based HDA codec drivers and the more modern ASoC (ALSA SoC) codec driver framework, which both utilize shared code paths for codec initialization and cleanup but operate under different lifecycle management paradigms.
The technical root cause of this vulnerability lies in the improper handling of the preset field within the snd_hda_codec structure during the cleanup process for unbound ASoC sound cards. When ASoC codec drivers are unloaded and reloaded multiple times during the system's operational lifetime, the function snd_hda_codec_cleanup_for_unbind() incorrectly unsets the preset field, which is typically assigned only once during the initial device/driver matching phase. This design flaw creates a fundamental mismatch between the expectations of the snd_hda_codec_device_new() function, which requires a valid snd_card instance pointer, and the actual state of the codec during module reload scenarios. The problem becomes particularly acute because ASoC sound cards can be unbound from the system without the underlying codec device being completely removed, leading to inconsistent state management across driver lifecycle operations.
The operational impact of this vulnerability extends beyond simple system crashes, potentially affecting audio functionality and system stability in embedded and desktop environments where audio drivers undergo frequent reloading operations. Attackers could exploit this weakness to cause denial of service conditions by triggering the specific sequence of unbinding and reloading operations that leads to null pointer dereference exceptions. The vulnerability is particularly concerning in server and embedded systems where audio subsystems may be actively managed through dynamic module loading/unloading processes, as these scenarios create predictable conditions for the exploit to occur. This issue demonstrates the complexity of maintaining backward compatibility while supporting multiple driver frameworks within the same kernel subsystem, where shared code paths between different architectural approaches can introduce subtle but critical race conditions and state management errors.
Mitigation strategies for CVE-2023-52736 require immediate kernel updates to the patched version that addresses the preset field management during codec cleanup operations. System administrators should prioritize applying the relevant security patches from their distribution vendors, particularly those that include the specific fix for snd_hda_codec_cleanup_for_unbind() function behavior. Organizations running embedded systems or servers with dynamic audio driver management should implement monitoring for audio subsystem instability and establish procedures for regular kernel updates to prevent exploitation of this vulnerability. The fix implements proper state management that preserves the preset field during unbind operations while allowing proper cleanup for actual device removal scenarios, addressing the core conflict between ASoC driver reload behavior and traditional HDA codec initialization patterns. This vulnerability aligns with CWE-476 which describes NULL Pointer Dereference conditions, and could be categorized under ATT&CK technique T1499.004 for endpoint denial of service through audio subsystem manipulation.