CVE-2022-20118 in Android
Summary
by MITRE • 05/11/2022
In ion_ioctl and related functions of ion.c, there is a possible use after free due to a race condition. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-205707793References: N/A
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Analysis
by VulDB Data Team • 05/13/2022
The vulnerability identified as CVE-2022-20118 resides within the Android kernel's ion memory management subsystem, specifically in the ion_ioctl function and associated handlers within the ion.c source file. This represents a critical security flaw that exploits a race condition inherent in the kernel's memory allocation and deallocation processes. The ion subsystem serves as a fundamental component for managing shared memory buffers across various Android components including graphics rendering, multimedia processing, and hardware abstraction layers, making it a prime target for privilege escalation attacks.
The technical flaw manifests as a use-after-free condition that occurs when multiple threads or processes access the same memory region simultaneously without proper synchronization mechanisms. When ion_ioctl processes memory allocation requests, the race condition allows an attacker to manipulate the timing of memory deallocation and subsequent reuse, creating opportunities for memory corruption. This vulnerability is particularly dangerous because it operates at the kernel level where memory corruption can directly translate into arbitrary code execution. The flaw stems from inadequate locking mechanisms during the ioctl processing flow, specifically when handling memory buffer operations that involve complex state transitions between allocated and freed memory regions.
The operational impact of this vulnerability extends beyond simple memory corruption, presenting a direct path for local privilege escalation attacks. An attacker with normal user privileges can leverage this race condition to gain kernel-level access, effectively bypassing Android's security model and gaining complete control over the device. The exploitation requires no additional execution privileges and does not necessitate user interaction, making it particularly dangerous in environments where untrusted applications might be running. This vulnerability affects Android kernel versions and impacts all devices running affected Android builds, potentially compromising millions of devices globally. The attack surface is broad as ion is extensively used across Android's multimedia and graphics frameworks, including surfaceflinger, media codecs, and graphics drivers.
Mitigation strategies for CVE-2022-20118 should focus on implementing proper synchronization mechanisms within the ion subsystem to prevent race conditions during memory allocation and deallocation operations. The most effective approach involves adding appropriate mutex locks or other concurrency control mechanisms around critical sections of the ioctl handler code, ensuring that memory operations complete atomically without interference from concurrent processes. Android security patches typically address this by introducing proper locking primitives and validating memory states before and after operations. Organizations should also implement kernel hardening measures including stack canaries, kernel address space layout randomization, and control flow integrity checks to reduce the effectiveness of exploitation attempts. This vulnerability aligns with CWE-362, which describes race conditions in concurrent programming, and maps to ATT&CK technique T1068, which covers local privilege escalation through kernel exploits. Regular security updates and kernel patch management remain essential defensive measures against this class of vulnerabilities.