CVE-2024-38541 in Linux
Summary
by MITRE • 06/19/2024
In the Linux kernel, the following vulnerability has been resolved:
of: module: add buffer overflow check in of_modalias()
In of_modalias(), if the buffer happens to be too small even for the 1st snprintf() call, the len parameter will become negative and str parameter (if not NULL initially) will point beyond the buffer's end. Add the buffer overflow check after the 1st snprintf() call and fix such check after the strlen() call (accounting for the terminating NUL char).
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Analysis
by VulDB Data Team • 10/04/2025
The vulnerability identified as CVE-2024-38541 resides within the Linux kernel's device tree subsystem, specifically in the of_modalias() function responsible for generating modalias strings for device tree nodes. This function serves a critical role in device identification and driver matching processes, making it a potential target for exploitation. The flaw manifests as a buffer overflow condition that can occur during the construction of device identification strings, particularly when dealing with devices that have exceptionally long or complex device tree properties. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, representing a fundamental memory safety issue that could potentially allow attackers to execute arbitrary code or cause system instability.
The technical implementation of this vulnerability occurs in the of_modalias() function where multiple snprintf() operations are performed to construct the modalias string. When the initial buffer allocation proves insufficient for the first snprintf() call, the len parameter becomes negative due to the calculation logic. This negative value subsequently causes the str parameter to point beyond the allocated buffer boundaries, creating a classic buffer overflow scenario. The issue is particularly concerning because device tree nodes can contain extensive property data from various hardware components, making buffer size calculations challenging. The vulnerability demonstrates poor input validation and insufficient boundary checking that fails to account for all possible string length scenarios during the modalias string generation process, potentially leading to memory corruption that could be exploited by malicious actors.
The operational impact of CVE-2024-38541 extends beyond simple system instability, as it represents a potential attack vector that could be leveraged by adversaries with access to device tree manipulation capabilities. The vulnerability affects systems that utilize device tree mechanisms for hardware enumeration and driver loading, which encompasses a broad range of embedded systems, servers, and desktop environments running Linux kernels. Attackers could potentially exploit this condition to execute arbitrary code with kernel privileges, leading to complete system compromise. The vulnerability's exploitation would likely require specific conditions related to device tree node manipulation and could be particularly dangerous in embedded systems or virtualized environments where device tree modifications might be more accessible. The issue is particularly relevant in contexts where the kernel handles untrusted device tree data from external sources, such as firmware updates or hardware detection in virtualized environments.
Mitigation strategies for CVE-2024-38541 should focus on implementing robust buffer overflow protections and input validation mechanisms within the kernel's device tree subsystem. The fix involves adding proper buffer overflow checks immediately after the first snprintf() call and ensuring that subsequent length calculations account for the terminating null character. System administrators should prioritize applying kernel updates that contain the patched version of of_modalias() function, which typically involves updating to kernel versions that include the specific buffer overflow protections. Organizations should also implement monitoring for unusual device tree activity or unexpected kernel behavior that might indicate exploitation attempts. The fix aligns with ATT&CK technique T1068 by addressing a privilege escalation vector, and follows security best practices outlined in the Linux kernel security guidelines. Additionally, implementing kernel lockdown mechanisms and restricting device tree modifications in sensitive environments can provide additional layers of protection against potential exploitation of this vulnerability.