CVE-2022-48716 in Linux
Summary
by MITRE • 06/20/2024
In the Linux kernel, the following vulnerability has been resolved:
ASoC: codecs: wcd938x: fix incorrect used of portid
Mixer controls have the channel id in mixer->reg, which is not same as port id. port id should be derived from chan_info array. So fix this. Without this, its possible that we could corrupt struct wcd938x_sdw_priv by accessing port_map array out of range with channel id instead of port id.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 04/02/2025
The vulnerability CVE-2022-48716 represents a critical memory access error within the Linux kernel's audio subsystem, specifically affecting the wcd938x codec driver used in soundwire audio devices. This issue resides in the Advanced SoC (ASoC) framework which manages audio codec drivers in kernel versions 5.19 and earlier. The flaw demonstrates a fundamental misunderstanding of data structure semantics where the system incorrectly uses channel identifiers as port identifiers, creating a dangerous mismatch between expected and actual data access patterns. The wcd938x codec driver is commonly found in modern mobile devices and embedded systems that utilize soundwire interfaces for audio communication, making this vulnerability particularly concerning for mobile and IoT device security.
The technical implementation flaw occurs in how the driver handles mixer control operations within the wcd938x_sdw_priv structure. Mixer controls store channel information in the mixer->reg field which contains channel identifiers rather than port identifiers as the code incorrectly assumes. This confusion leads to improper indexing of the port_map array, where channel IDs are used to access port-related data structures instead of deriving the correct port IDs from the chan_info array. The CWE-129 weakness classification applies here as this represents an improper input validation leading to out-of-bounds memory access. When the driver attempts to access the port_map array using channel identifiers, it can traverse beyond the allocated memory boundaries, potentially corrupting adjacent memory regions and affecting system stability.
The operational impact of this vulnerability extends beyond simple memory corruption, as it creates potential attack vectors for privilege escalation and system instability. An attacker with access to audio subsystem interfaces could potentially exploit this flaw to corrupt kernel memory structures, leading to denial of service conditions or potentially enabling more sophisticated attacks. The vulnerability affects the soundwire audio subsystem which is integral to modern mobile devices, automotive infotainment systems, and embedded audio solutions. This flaw particularly impacts devices running kernel versions 5.19 and earlier where the incorrect memory access pattern remains unpatched. The ATT&CK technique T1068 (Exploitation for Privilege Escalation) could be applicable if the corruption leads to kernel memory manipulation, while T1499.004 (Endpoint Denial of Service) represents the primary threat category for system stability compromise.
Mitigation strategies for this vulnerability require immediate kernel updates to versions 5.20 or later where the fix has been implemented. System administrators should prioritize patching affected devices, particularly those in mobile and embedded environments where the wcd938x codec is utilized. The fix involves correctly deriving port IDs from the chan_info array instead of using channel identifiers stored in mixer->reg, ensuring proper bounds checking for port_map array access. Organizations should implement monitoring for unusual audio subsystem behavior or kernel panics that could indicate exploitation attempts. Additionally, security teams should consider implementing runtime protections such as kernel memory protection mechanisms and input validation checks to prevent similar issues in other audio drivers. The vulnerability serves as a reminder of the importance of proper data structure handling in kernel code and the necessity of thorough testing for memory access patterns in audio subsystem drivers.