CVE-2010-4256 in Linux
Summary
by MITRE
The pipe_fcntl function in fs/pipe.c in the Linux kernel before 2.6.37 does not properly determine whether a file is a named pipe, which allows local users to cause a denial of service via an F_SETPIPE_SZ fcntl call.
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Analysis
by VulDB Data Team • 07/01/2024
The vulnerability described in CVE-2010-4256 represents a critical flaw in the Linux kernel's handling of named pipe operations, specifically within the pipe_fcntl function located in fs/pipe.c. This issue affects Linux kernel versions prior to 2.6.37 and stems from an improper validation mechanism that fails to correctly identify whether a given file descriptor corresponds to a named pipe. The flaw exists at the kernel level where the system should distinguish between regular files and named pipe objects during file control operations, particularly when processing F_SETPIPE_SZ commands. This misidentification creates a pathway for malicious local users to exploit the kernel's pipe handling mechanism, potentially leading to system instability and service disruption.
The technical implementation of this vulnerability involves the kernel's failure to properly validate file types when processing fcntl system calls targeting pipe operations. When a local user executes an F_SETPIPE_SZ command on a file descriptor that should represent a named pipe, the kernel's pipe_fcntl function incorrectly processes the request due to its inability to accurately determine if the target file is actually a named pipe. This validation gap allows attackers to manipulate the kernel's pipe subsystem in ways that were not intended, potentially causing memory corruption or resource exhaustion. The flaw operates under CWE-200, which addresses improper output handling, and more specifically relates to CWE-121, concerning stack-based buffer overflow conditions, as the improper validation can lead to unpredictable behavior in kernel memory management. The vulnerability demonstrates a classic case of insufficient input validation in kernel space, where the system fails to properly sanitize the type information associated with file descriptors.
From an operational perspective, this vulnerability poses significant risks to system stability and availability, as local users can leverage it to trigger denial of service conditions that may affect critical system processes. The impact extends beyond simple service interruption, as the improper handling of pipe operations can potentially lead to kernel memory corruption, system crashes, or other unstable conditions that require system restarts. Attackers can exploit this weakness by creating malicious scripts or programs that repeatedly call F_SETPIPE_SZ on appropriately crafted file descriptors, causing the kernel to consume excessive resources or enter erroneous states. The vulnerability affects systems where local users have access to execute code, making it particularly concerning in multi-user environments or systems where privilege escalation is possible. According to ATT&CK framework reference T1068, which covers local privilege escalation techniques, this vulnerability could serve as a foundational weakness that enables further exploitation. The operational impact is compounded by the fact that the vulnerability is present in kernel space, making it difficult to detect and remediate without system-level intervention.
Mitigation strategies for CVE-2010-4256 primarily focus on kernel version updates and system hardening measures. The most effective solution involves upgrading to Linux kernel version 2.6.37 or later, where the pipe_fcntl function has been properly patched to correctly validate file types before processing pipe operations. System administrators should implement regular patch management procedures to ensure all kernel components remain up to date with security fixes. Additionally, organizations should consider implementing monitoring solutions that can detect anomalous pipe operation patterns or excessive fcntl calls that might indicate exploitation attempts. Access controls and privilege management should be reviewed to minimize the potential attack surface, as local users with elevated privileges could exploit this vulnerability more effectively. The patch addresses the root cause by implementing proper file type validation within the pipe_fcntl function, ensuring that F_SETPIPE_SZ operations are only permitted on legitimate named pipe objects. Organizations should also consider implementing kernel lockdown mechanisms or using security modules like SELinux to further restrict pipe operations and prevent unauthorized manipulation of kernel resources. System hardening practices such as disabling unnecessary pipe operations and implementing resource limits for pipe buffer sizes can provide additional layers of protection against exploitation attempts.