CVE-2022-48863 in Linux
Summary
by MITRE • 07/16/2024
In the Linux kernel, the following vulnerability has been resolved:
mISDN: Fix memory leak in dsp_pipeline_build()
dsp_pipeline_build() allocates dup pointer by kstrdup(cfg), but then it updates dup variable by strsep(&dup, "|"). As a result when it calls kfree(dup), the dup variable contains NULL.
Found by Linux Driver Verification project (linuxtesting.org) with SVACE.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/27/2024
The vulnerability CVE-2022-48863 resides within the Linux kernel's mISDN subsystem, specifically in the dsp_pipeline_build() function where a memory leak occurs due to improper pointer management during string processing operations. This flaw represents a classic case of resource management error that can lead to system instability and potential denial of service conditions. The issue was identified through automated verification processes conducted by the Linux Driver Verification project, highlighting the importance of systematic testing in kernel development environments.
The technical implementation of this vulnerability stems from a fundamental misunderstanding of how strsep() function operates in relation to memory allocation and pointer updates. When the function allocates memory using kstrdup(cfg), it creates a duplicate of the configuration string and assigns it to the dup pointer. However, subsequent execution of strsep(&dup, "|") modifies the dup variable itself by advancing it to point to the next segment of the string, effectively changing the original pointer value that was allocated by kstrdup. This pointer manipulation results in the original memory allocation being lost, creating a memory leak that persists until the system reboots or the module is unloaded. The function then attempts to free this modified pointer which contains NULL, rendering the kfree() operation ineffective and leaving the originally allocated memory unreclaimed.
The operational impact of this vulnerability extends beyond simple memory consumption issues as it can contribute to progressive system degradation and potential system crashes. In embedded systems or environments with limited memory resources, such memory leaks can accumulate over time and eventually exhaust available memory pools, leading to system instability or complete system failure. The vulnerability affects systems running Linux kernels that include the mISDN subsystem, particularly those utilizing ISDN (Integrated Services Digital Network) functionality for telecommunications services. Attackers could potentially exploit this memory leak to cause denial of service conditions by triggering the vulnerable code path repeatedly, though direct exploitation for privilege escalation or arbitrary code execution is not typically possible given the nature of the flaw.
Mitigation strategies for this vulnerability involve applying the official kernel patch that corrects the pointer management logic in the dsp_pipeline_build() function. The fix requires ensuring that the original pointer value returned by kstrdup() is preserved and used for kfree() operations, while any subsequent string manipulation should operate on temporary variables or maintain separate references to the original allocation. System administrators should prioritize updating their kernel versions to include this patch, particularly in production environments where ISDN functionality is utilized. Additionally, monitoring for memory usage patterns and implementing automated alerts for memory exhaustion conditions can help detect potential exploitation attempts. The vulnerability aligns with CWE-401: Improper Release of Memory and can be classified under ATT&CK technique T1499.004: Endpoint Denial of Service, as it can lead to system resource exhaustion and denial of service conditions. Regular kernel updates and comprehensive testing of driver components remain essential practices for maintaining system security and stability in the face of such memory management vulnerabilities.