CVE-2024-26946 in Linux
Summary
by MITRE • 05/01/2024
In the Linux kernel, the following vulnerability has been resolved:
kprobes/x86: Use copy_from_kernel_nofault() to read from unsafe address
Read from an unsafe address with copy_from_kernel_nofault() in arch_adjust_kprobe_addr() because this function is used before checking the address is in text or not. Syzcaller bot found a bug and reported the case if user specifies inaccessible data area, arch_adjust_kprobe_addr() will cause a kernel panic.
[ mingo: Clarified the comment. ]
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Analysis
by VulDB Data Team • 01/26/2026
The vulnerability CVE-2024-26946 represents a critical kernel-level issue within the Linux operating system that affects the kprobes subsystem on x86 architectures. This flaw exists in the arch_adjust_kprobe_addr() function where the kernel attempts to read from memory addresses without proper validation of address accessibility. The vulnerability stems from a timing issue in the address validation process where copy_from_kernel_nofault() is invoked before checking whether the target address falls within executable text regions. This premature access to potentially inaccessible memory locations creates a pathway for kernel panics and system instability when userspace applications provide invalid memory addresses to kprobe mechanisms.
The technical implementation of this vulnerability manifests through improper memory access patterns within the kernel's debugging and profiling infrastructure. The kprobes subsystem is designed to allow dynamic tracing and debugging of kernel functions by setting breakpoints at specific memory addresses. However, the arch_adjust_kprobe_addr() function fails to properly validate memory addresses before attempting to read from them using copy_from_kernel_nofault(), which is intended for safe kernel memory access but cannot prevent access violations when the target address is genuinely inaccessible. This flaw creates a race condition where the kernel attempts to dereference memory locations that may not be mapped or accessible, leading to immediate system crashes.
The operational impact of CVE-2024-26946 extends beyond simple system crashes to represent a potential denial-of-service vector that could be exploited by malicious actors. When a kernel panic occurs due to this vulnerability, the entire system becomes unavailable, requiring manual reboot or potentially allowing for more sophisticated exploitation techniques. The vulnerability affects all Linux kernel versions that implement kprobes functionality on x86 platforms, making it particularly concerning for production environments where system stability is paramount. The issue was identified through automated testing by the syzcaller bot, which demonstrated that user-specified inaccessible data areas could trigger the kernel panic condition, highlighting the importance of proper input validation in kernel space operations.
Mitigation strategies for CVE-2024-26946 require immediate kernel updates to address the flawed address validation logic in arch_adjust_kprobe_addr(). System administrators should prioritize patching affected systems to ensure the proper sequence of address validation before memory access operations. The fix involves restructuring the function to perform address accessibility checks before invoking copy_from_kernel_nofault(), which aligns with established kernel security practices and follows the principle of least privilege. This vulnerability demonstrates the importance of proper kernel memory management and access control, particularly in debugging subsystems where invalid memory references could lead to catastrophic system failures. Organizations should also implement monitoring for unusual kprobe usage patterns that might indicate attempted exploitation attempts, as the vulnerability could potentially be leveraged in more advanced attack scenarios beyond simple denial-of-service.
This vulnerability maps directly to CWE-125: Uninitialized Memory Read and CWE-787: Out-of-bounds Write, as it involves accessing memory locations that may not be properly initialized or accessible. The ATT&CK framework categorizes this under T1059.006: System Scripting and T1566.001: Phishing, as the vulnerability could be exploited through malicious kernel module loading or debugging tools. The flaw represents a fundamental breakdown in kernel memory safety mechanisms that violates the principle of kernel space memory protection and demonstrates the critical need for comprehensive input validation in privileged execution contexts.