CVE-2022-49852 in Linux
Summary
by MITRE • 05/01/2025
In the Linux kernel, the following vulnerability has been resolved:
riscv: process: fix kernel info leakage
thread_struct's s[12] may contain random kernel memory content, which
may be finally leaked to userspace. This is a security hole. Fix it by clearing the s[12] array in thread_struct when fork.
As for kthread case, it's better to clear the s[12] array as well.
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Analysis
by VulDB Data Team • 01/23/2026
The vulnerability described in CVE-2022-49852 represents a critical information disclosure issue within the Linux kernel's RISC-V architecture implementation. This security flaw specifically affects the thread_struct data structure which contains the s[12] array that may retain kernel memory content from previous operations. The vulnerability arises from insufficient memory sanitization during process creation, creating a potential pathway for attackers to access sensitive kernel data that should remain confidential. The issue impacts systems running Linux kernels with RISC-V architecture support, particularly those utilizing the fork() system call for process creation, where the s[12] array contents are not properly cleared before being exposed to user space contexts.
The technical implementation flaw stems from the improper handling of the thread_struct s[12] array during process forking operations. When a new process is created through fork(), the kernel does not adequately clear the s[12] array elements that may contain residual kernel memory contents from previous operations or other processes. This memory leakage occurs because the array retains data from kernel memory regions that should not be accessible to user space applications. The vulnerability is particularly concerning as it allows for potential information disclosure attacks where malicious code could potentially extract kernel memory addresses, stack contents, or other sensitive information that could be used for further exploitation. This flaw directly relates to CWE-200, which addresses the improper exposure of sensitive information, and demonstrates a classic case of information leakage through improper memory management.
The operational impact of this vulnerability extends beyond simple information disclosure, potentially enabling sophisticated attack vectors that could compromise system security. Attackers could leverage this information leak to perform advanced exploitation techniques such as kernel address space layout randomization (ASLR) bypass attempts, where the leaked memory contents could reveal kernel memory layout details. The vulnerability affects both regular process creation and kernel thread (kthread) scenarios, indicating that the issue is not limited to user-space processes but also extends to kernel-level thread management. This comprehensive scope makes the vulnerability particularly dangerous as it could provide attackers with multiple attack surfaces to exploit, potentially leading to privilege escalation or complete system compromise. The security implications align with ATT&CK technique T1068, which involves exploiting vulnerabilities to gain elevated privileges, and T1566, which covers the use of vulnerabilities to obtain initial access.
The recommended mitigation strategy involves implementing proper memory clearing procedures during the fork() system call execution for thread_struct s[12] arrays. The fix requires modifying the kernel code to ensure that the s[12] array elements are explicitly cleared or zeroed out when new processes are created, preventing any residual kernel memory content from being exposed to user space. This approach aligns with secure coding practices that emphasize proper memory initialization and sanitization. System administrators should prioritize applying the kernel patches that implement this fix, as the vulnerability creates a persistent security risk that could be exploited by malicious actors. Additionally, monitoring for unusual memory access patterns or potential exploitation attempts could provide early detection of any attempts to leverage this information leak. Organizations should also consider implementing additional security controls such as kernel memory protection mechanisms and regular security assessments to identify and remediate similar vulnerabilities in their systems.