CVE-2024-36934 in Linux
Summary
by MITRE • 05/30/2024
In the Linux kernel, the following vulnerability has been resolved:
bna: ensure the copied buf is NUL terminated
Currently, we allocate a nbytes-sized kernel buffer and copy nbytes from userspace to that buffer. Later, we use sscanf on this buffer but we don't ensure that the string is terminated inside the buffer, this can lead to OOB read when using sscanf. Fix this issue by using memdup_user_nul instead of memdup_user.
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Analysis
by VulDB Data Team • 01/22/2026
The vulnerability identified as CVE-2024-36934 resides within the Linux kernel's bna driver component, specifically affecting how user-space data is handled during kernel operations. This issue demonstrates a classic buffer management flaw that can lead to serious security implications when processing untrusted input. The bna driver is responsible for managing Brocade Network Adapter hardware, making this vulnerability particularly concerning for network infrastructure systems where kernel-level stability and security are paramount. The flaw manifests in the improper handling of string data when copying from user-space to kernel-space buffers, creating potential attack vectors that could be exploited by malicious actors.
The technical root cause of this vulnerability stems from the improper use of memory copying functions within the kernel's memory management subsystem. When the driver receives data from user-space applications, it allocates a kernel buffer of exactly nbytes size and copies the data from userspace into this buffer. However, the implementation fails to ensure proper null termination of the copied string data within the kernel buffer. This omission creates a condition where the subsequent sscanf function call operates on potentially unterminated string data, leading to out-of-bounds memory reads. The flaw is classified as a buffer overflow vulnerability because the sscanf function, when processing unterminated strings, may read beyond the allocated buffer boundaries, accessing adjacent memory locations that could contain sensitive data or system information.
The operational impact of this vulnerability extends beyond simple memory access issues to potentially enable more sophisticated attacks. When an attacker can manipulate the input data to the bna driver, they may be able to cause the kernel to read beyond allocated memory boundaries, potentially exposing kernel memory contents or causing system instability. This type of out-of-bounds read could lead to information disclosure, where sensitive kernel data becomes accessible to user-space processes, or it could be leveraged as part of a broader exploitation chain. The vulnerability is particularly dangerous because it occurs in kernel space, meaning any successful exploitation could lead to privilege escalation or complete system compromise, making it a critical issue for system administrators and security professionals to address promptly.
The fix implemented for this vulnerability involves a straightforward but critical change in memory management practices. Instead of using the memdup_user function which does not guarantee null termination, the solution employs memdup_user_nul which ensures that the copied buffer is properly null-terminated. This change aligns with established security best practices for kernel memory handling and follows the principle of defensive programming. The fix addresses the core issue identified in the Common Weakness Enumeration catalog under CWE-121, which deals with stack-based buffer overflow conditions, and also relates to CWE-125, which covers out-of-bounds read vulnerabilities. From an operational security perspective, this fix represents a simple but effective mitigation that can be applied across all affected kernel versions without significant performance impact or system disruption. The solution also aligns with the MITRE ATT&CK framework's technique T1068, which covers "Exploitation for Privilege Escalation," as this vulnerability could potentially be exploited to gain elevated privileges within the kernel space.
The resolution of CVE-2024-36934 demonstrates the importance of proper memory boundary checking in kernel-level code and highlights the critical need for thorough input validation in system drivers. This vulnerability serves as a reminder that even seemingly simple memory management operations can have far-reaching security implications when not properly implemented. The fix not only resolves the immediate out-of-bounds read issue but also reinforces proper kernel security practices that should be applied across all driver implementations. Organizations should prioritize applying this patch to all systems running affected kernel versions, particularly those hosting network infrastructure components that utilize Brocade Network Adapters, as the potential for exploitation remains high given the kernel-space nature of the vulnerability and the broad attack surface it presents.