CVE-2022-20008 in Android
Summary
by MITRE • 05/11/2022
In mmc_blk_read_single of block.c, there is a possible way to read kernel heap memory due to uninitialized data. This could lead to local information disclosure if reading from an SD card that triggers errors, with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-216481035References: Upstream kernel
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Analysis
by VulDB Data Team • 05/18/2025
This vulnerability exists within the mmc_blk_read_single function in the block.c file of the Android kernel, representing a critical information disclosure flaw that allows unauthorized access to kernel heap memory. The issue stems from the improper handling of uninitialized data during SD card read operations, specifically when error conditions occur during data transfer from storage devices. The vulnerability manifests when the kernel attempts to read from an SD card that triggers an error condition, creating an opportunity for local attackers to extract sensitive kernel memory contents through carefully crafted read operations. The flaw does not require any additional execution privileges or user interaction for exploitation, making it particularly dangerous as it can be triggered automatically during normal device operation when SD card errors occur.
The technical implementation of this vulnerability aligns with CWE-248, an unspecified vulnerability that specifically addresses the exposure of uninitialized memory contents, and falls under the broader category of information disclosure vulnerabilities. The root cause occurs during the memory management process where the kernel fails to properly initialize memory buffers before reading data from the SD card interface. This uninitialized memory may contain remnants of previous operations, sensitive data structures, or cryptographic keys that could be accessed by malicious actors. The attack vector leverages the kernel's error handling mechanism during SD card communication, where the system attempts to read corrupted or incomplete data from storage devices, inadvertently exposing kernel heap contents to unauthorized access.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with access to potentially sensitive kernel memory that could contain confidential data structures, encryption keys, or other critical system information. In Android environments, this vulnerability could enable attackers to extract information about the device's internal state, potentially leading to further exploitation opportunities such as privilege escalation or detailed system reconnaissance. The local nature of the vulnerability means that any process running with standard user privileges can trigger the exploit, making it particularly concerning for mobile device security where users may not be aware of the underlying kernel operations. The lack of user interaction requirements means that the vulnerability can be exploited automatically during normal device usage when SD card errors occur.
Mitigation strategies should focus on implementing proper memory initialization practices within the kernel's block device drivers, specifically ensuring that all memory buffers are properly initialized before data read operations. The recommended approach involves modifying the mmc_blk_read_single function to explicitly initialize memory regions before attempting to read from SD card interfaces, preventing the exposure of uninitialized heap data. Additionally, implementing proper error handling and validation checks during SD card read operations can help prevent the exploitation of this vulnerability by ensuring that corrupted or incomplete data does not trigger memory access patterns that expose kernel heap contents. System administrators should also consider applying kernel updates that address this specific vulnerability and monitor for any signs of exploitation attempts in device logs or security monitoring systems. The fix should align with secure coding practices outlined in the CERT Secure Coding Standards and the Android Security Best Practices documentation to prevent similar vulnerabilities from occurring in future kernel implementations.