CVE-2011-2184 in Linux
Summary
by MITRE
The key_replace_session_keyring function in security/keys/process_keys.c in the Linux kernel before 2.6.39.1 does not initialize a certain structure member, which allows local users to cause a denial of service (NULL pointer dereference and OOPS) or possibly have unspecified other impact via a KEYCTL_SESSION_TO_PARENT argument to the keyctl function, a different vulnerability than CVE-2010-2960.
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Analysis
by VulDB Data Team • 11/18/2021
The vulnerability identified as CVE-2011-2184 resides within the Linux kernel's key management subsystem, specifically in the key_replace_session_keyring function located in security/keys/process_keys.c. This flaw represents a classic case of improper initialization where a critical structure member remains uninitialized during kernel operation. The vulnerability affects Linux kernel versions prior to 2.6.39.1 and demonstrates how seemingly minor coding oversights can lead to significant security implications. The issue manifests when the KEYCTL_SESSION_TO_PARENT argument is passed to the keyctl system call, creating a pathway for exploitation that differs from previously known vulnerabilities such as CVE-2010-2960.
The technical root cause of this vulnerability stems from the failure to properly initialize a structure member within the key_replace_session_keyring function. When a local user executes the keyctl command with the SESSION_TO_PARENT argument, the kernel processes this request through the key management subsystem. The uninitialized structure member creates a condition where subsequent operations attempt to dereference a NULL pointer, leading to kernel panic and system crash. This NULL pointer dereference represents a fundamental violation of memory safety principles and aligns with CWE-476, which specifically addresses NULL pointer dereference vulnerabilities. The vulnerability's impact extends beyond simple denial of service as it could potentially allow for more sophisticated exploitation techniques depending on the system configuration and available attack surface.
From an operational perspective, this vulnerability presents a significant risk to Linux systems running affected kernel versions, particularly in environments where local user access is prevalent. The local privilege escalation potential, while not explicitly stated in the original description, represents a logical extension of the vulnerability's impact given that local users can trigger the conditions necessary for exploitation. The system stability implications are severe, as the kernel OOPS condition and subsequent system crash can result in complete service interruption. This vulnerability directly impacts the kernel's ability to maintain consistent operation and can be leveraged by malicious actors to create persistent denial of service conditions that are difficult to detect and remediate.
The exploitation of this vulnerability requires local user access and involves crafting specific keyctl commands with the SESSION_TO_PARENT argument, making it relatively straightforward for attackers who already have access to the system. This characteristic places the vulnerability in the ATT&CK framework under the T1068 technique for local privilege escalation, though the immediate impact is more focused on system stability than privilege elevation. Organizations should prioritize patching this vulnerability as part of their regular security maintenance procedures, as the kernel version 2.6.39.1 and later contain the necessary fixes. The remediation process involves updating to the patched kernel version, which ensures proper initialization of the affected structure member and eliminates the NULL pointer dereference condition that enables the vulnerability. Security teams should also implement monitoring for unusual keyctl activity patterns that might indicate exploitation attempts, particularly in environments where multiple users have local access to systems.