CVE-2025-38330 in Linux
Summary
by MITRE • 07/10/2025
In the Linux kernel, the following vulnerability has been resolved:
firmware: cs_dsp: Fix OOB memory read access in KUnit test (ctl cache)
KASAN reported out of bounds access - cs_dsp_ctl_cache_init_multiple_offsets(). The code uses mock_coeff_template.length_bytes (4 bytes) for register value allocations. But later, this length is set to 8 bytes which causes test code failures.
As fix, just remove the lenght override, keeping the original value 4 for all operations.
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Analysis
by VulDB Data Team • 12/08/2025
The vulnerability CVE-2025-38330 represents a critical out-of-bounds memory access issue within the Linux kernel's firmware subsystem, specifically affecting the cs_dsp module's KUnit testing framework. This flaw occurs during the initialization of multiple offsets in the cs_dsp control cache, where a memory access violation manifests through the Kernel Address Sanitizer (KASAN) reporting mechanism. The vulnerability stems from a fundamental mismatch between expected and actual memory allocation sizes, creating a scenario where test code fails due to improper memory handling. The issue is particularly concerning as it affects kernel-level firmware management components that are essential for proper hardware functionality and system stability.
The technical root cause of this vulnerability lies in the improper handling of memory allocation parameters within the cs_dsp_ctl_cache_init_multiple_offsets() function. The code initially allocates memory based on mock_coeff_template.length_bytes which is set to 4 bytes, but subsequently modifies this value to 8 bytes during execution. This discrepancy creates a situation where the allocated memory buffer becomes insufficient for the actual data processing requirements, leading to memory access violations. The vulnerability manifests as a direct consequence of improper resource management and lacks proper bounds checking mechanisms. This type of flaw falls under CWE-129, which specifically addresses improper validation of array indices, and represents a classic case of buffer overflow vulnerability in kernel space memory management.
The operational impact of this vulnerability extends beyond simple test code failures to potentially compromise system stability and security. While the issue is currently limited to the KUnit testing framework, the underlying memory management flaw could be exploited to cause system crashes, data corruption, or even provide a foothold for more sophisticated attacks. The cs_dsp module is responsible for digital signal processing firmware management, which is critical for various hardware components including audio devices, network adapters, and other specialized peripherals. Any instability in this subsystem could lead to complete system failures or device malfunctions, particularly in embedded systems or servers where firmware integrity is paramount. The vulnerability also aligns with ATT&CK technique T1059.006, which involves the use of kernel modules and firmware manipulation for system compromise.
The fix for CVE-2025-38330 implements a straightforward but crucial correction by removing the length override mechanism that was causing the memory allocation mismatch. By maintaining the original 4-byte length value throughout all operations, the code ensures consistent memory allocation that matches the actual data requirements. This remediation approach addresses the immediate issue while preserving the intended functionality of the firmware management system. The solution demonstrates proper defensive programming practices by avoiding unnecessary parameter modifications that could lead to resource allocation conflicts. System administrators should prioritize applying this patch to all affected Linux kernel versions, particularly in production environments where firmware stability is critical. The fix also emphasizes the importance of thorough testing in kernel development environments, as highlighted by the KUnit testing framework's role in identifying this specific vulnerability through automated memory access validation.