CVE-2026-98053
Summary
by MITRE • 09/25/2026
In the Linux kernel, the following vulnerability has been resolved:
ASoC: Intel: avs: Refactor and fix init_config access
Existing code accesses enties found in ->init_configs array through indexes that are part of ->config_ids array. Those two are limited by: ->num_init_configs and ->num_config_ids respectively. Using ID larger or equal to ->num_init_configs leads to out-of-bounds access:
avs_path_module_send_init_configs() loop: (...) &acomp->tplg->init_configs[ids[i]]
^ out-of-bounds candidate
Rather than adding another if-statement, refactor the code. There is no need to store the IDs, have a list of pointers to actual config-entries instead. As the verification of ->init_config entries does not differ from verification of other types that are part of the topology.c file, simply reuse the code.
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Analysis
by VulDB Data Team • 09/25/2026
The Linux kernel's Advanced Sound Card (ASoC) subsystem for Intel Audio Voice Stream (AVS) drivers contains a critical memory safety vulnerability rooted in improper array index validation within the topology configuration handling logic. This flaw specifically affects the avs_path_module_send_init_configs function, which is responsible for processing initialization configurations required to set up audio path modules during driver initialization or runtime reconfiguration. The underlying technical issue stems from a mismatch between how configuration identifiers are stored and how they are subsequently accessed by the kernel code. Specifically, the existing implementation relies on an array of identifier values, referred to as config_ids, which serve as indices into another separate data structure containing the actual configuration entries, known as init_configs. This design assumes that every value present in the config_ids array corresponds to a valid index within the bounds of the init_configs array. However, this assumption is not rigorously enforced by the existing validation logic before access occurs.
The core technical flaw manifests when an identifier stored in the config_ids array holds a value greater than or equal to the number of entries defined in the num_init_configs field. In such scenarios, the loop within avs_path_module_send_init_configs attempts to dereference &acomp->tplg->init_configs[ids[i]] using this invalid index. Because C arrays do not perform automatic bounds checking at runtime, accessing an element beyond the allocated memory region results in a classic out-of-bounds read vulnerability. This type of error falls squarely under CWE-125, which describes Out-of-Bounds Read conditions where software reads data past the end or before the beginning of the intended buffer. The severity of this issue is compounded by its potential to lead to information disclosure if the adjacent memory contains sensitive kernel data structures, or potentially cause a denial of service through a general protection fault or page fault that crashes the kernel process handling audio operations.
From an operational perspective, this vulnerability impacts systems utilizing Intel AVS-based audio hardware where topology configurations are dynamically loaded or modified. An attacker with local access to the system could potentially exploit this flaw by crafting malformed ALSA topology data files or triggering specific driver states that cause invalid identifiers to be processed. While exploitation typically requires some level of privilege to interact with sound card configuration interfaces, the presence of such a bug in kernel-space code represents a significant security risk. It violates fundamental principles of secure coding regarding input validation and boundary checking. The vulnerability highlights the dangers of maintaining parallel data structures without strict synchronization between their sizes and access patterns.
The resolution involves refactoring the initialization logic to eliminate the dependency on index-based lookups that are prone to off-by-one or out-of-bounds errors. Instead of storing integer identifiers in a separate array and using them as indices, the updated code employs direct pointers to the actual configuration entries within the init_configs structure. This approach removes the intermediate step of indexing entirely, thereby making it impossible for an invalid identifier value to cause an out-of-bounds access because no arithmetic index calculation is performed against the bounds of the target array during retrieval. Furthermore, the fix integrates this logic with existing verification routines found in topology.c, ensuring that all configuration entries undergo consistent validation checks regardless of their type. This consolidation not only fixes the immediate security flaw but also improves code maintainability and reduces redundancy by reusing established safety mechanisms already present elsewhere in the subsystem.
To mitigate similar risks in other parts of the kernel or third-party drivers, developers should adhere to strict input validation practices that verify array indices against declared limits before any memory access occurs. Aligning with ATT&CK techniques related to initial access or privilege escalation via local exploits is less relevant here since this is a bug fix rather than an attack vector description, but understanding CWE-125 helps in auditing similar code patterns. Security engineers should prioritize refactoring legacy indexing mechanisms into direct pointer dereferences where possible, as it inherently reduces the surface area for index-related vulnerabilities. Regular static analysis and fuzzing of topology parsing routines are recommended to detect such boundary condition errors early in the development lifecycle before they reach production kernels.