CVE-2024-46792 in Linux
Summary
by MITRE • 09/18/2024
In the Linux kernel, the following vulnerability has been resolved:
riscv: misaligned: Restrict user access to kernel memory
raw_copy_{to,from}_user() do not call access_ok(), so this code allowed
userspace to access any virtual memory address.
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Analysis
by VulDB Data Team • 04/06/2026
The vulnerability identified as CVE-2024-46792 represents a critical security flaw in the Linux kernel's RISC-V architecture implementation that fundamentally undermines memory protection mechanisms. This issue specifically affects the misaligned memory access handling code within the kernel's user space memory management subsystem, creating a pathway for unauthorized memory access that violates fundamental security boundaries between user and kernel space. The flaw exists in the raw_copy_to_user() and raw_copy_from_user() functions which are designed to facilitate efficient memory transfers between user space and kernel space contexts. These functions operate without proper validation through the access_ok() mechanism that should normally verify memory access permissions and prevent userspace processes from accessing kernel memory regions.
The technical root cause of this vulnerability stems from the omission of access_ok() function calls within the raw_copy_{to,from}_user() implementations for RISC-V platforms. This omission creates a scenario where user space applications can potentially execute memory operations that target kernel virtual memory addresses without proper authorization checks. The access_ok() function serves as a crucial security gatekeeper that validates whether a given memory address range is accessible to the calling process, particularly when transitioning from user space to kernel space. When this validation is bypassed, the kernel's memory protection mechanisms become ineffective, allowing malicious userspace code to read or write to kernel memory locations that should remain protected. This vulnerability falls under the CWE-122 category of "Heap-based Buffer Overflow" and more specifically relates to improper access control mechanisms that enable unauthorized memory access patterns.
The operational impact of this vulnerability extends far beyond simple memory access violations, as it provides potential attackers with the ability to extract sensitive kernel data, modify kernel structures, and ultimately compromise the entire system integrity. Attackers could leverage this flaw to read kernel memory contents including cryptographic keys, credentials, and other sensitive information stored in kernel space. Additionally, the vulnerability enables write operations to kernel memory, potentially allowing for the modification of critical kernel data structures, function pointers, or system state variables. This capability represents a severe privilege escalation vector that could enable attackers to gain full system control, as demonstrated by similar vulnerabilities in the Linux kernel's memory management subsystem that have been exploited in the wild. The impact is particularly concerning on RISC-V systems where this flaw affects the fundamental memory access mechanisms that underpin all kernel operations.
Mitigation strategies for this vulnerability require immediate kernel updates that restore proper access validation to the raw_copy_{to,from}_user() functions, ensuring that access_ok() is called before any memory operations that cross user-kernel boundaries. System administrators should prioritize patching affected systems with the latest kernel releases that contain the fix for this vulnerability, as the risk of exploitation remains high given the nature of the flaw. Organizations should also implement monitoring for suspicious memory access patterns and ensure that kernel memory protection mechanisms remain intact through regular security audits. The fix aligns with the ATT&CK technique T1068 which covers 'Local Privilege Escalation' through kernel exploits, and T1547.001 which addresses 'Registry Run Keys / Startup Folder' but more specifically relates to the kernel memory protection bypasses that enable such escalations. System hardening measures including disabling unnecessary kernel modules and implementing strict memory access controls should complement the patching efforts to minimize the attack surface and prevent potential exploitation of similar vulnerabilities in the kernel's memory management subsystem.