CVE-2014-3631 in Linux
Summary
by MITRE
The assoc_array_gc function in the associative-array implementation in lib/assoc_array.c in the Linux kernel before 3.16.3 does not properly implement garbage collection, which allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact via multiple "keyctl newring" operations followed by a "keyctl timeout" operation.
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Analysis
by VulDB Data Team • 11/22/2024
The vulnerability identified as CVE-2014-3631 resides within the Linux kernel's associative array implementation, specifically in the assoc_array_gc function located in lib/assoc_array.c. This flaw represents a critical memory management issue that affects Linux kernel versions prior to 3.16.3, creating a pathway for local attackers to exploit improper garbage collection mechanisms. The vulnerability manifests through a sequence of keyctl operations that manipulate the kernel's key management system, ultimately leading to system instability and potential denial of service conditions.
The technical root cause of this vulnerability stems from inadequate garbage collection implementation within the associative array data structure. When multiple "keyctl newring" operations are executed followed by a "keyctl timeout" operation, the assoc_array_gc function fails to properly handle memory cleanup procedures. This improper handling results in dangling pointers and memory corruption that eventually leads to NULL pointer dereferences. The flaw operates at the kernel level, making it particularly dangerous as it can be exploited by any local user with access to the system, requiring no special privileges or network access for exploitation.
The operational impact of CVE-2014-3631 extends beyond simple denial of service, potentially enabling more severe consequences including system crashes and complete kernel oops conditions. Attackers can repeatedly perform the sequence of keyctl operations to exhaust system resources and trigger the memory corruption that leads to kernel panics. This vulnerability aligns with CWE-476 which describes NULL pointer dereference issues, and demonstrates characteristics consistent with ATT&CK technique T1499.004 for network denial of service. The vulnerability's exploitation path involves manipulating kernel data structures through user-space interfaces, making it particularly insidious as it bypasses traditional user-space security controls.
Mitigation strategies for this vulnerability primarily focus on kernel version updates to 3.16.3 or later, where the garbage collection implementation has been corrected. System administrators should prioritize patching affected systems as this vulnerability can be exploited by local users to cause system instability. Additionally, monitoring for unusual keyctl operations and implementing proper system hardening measures can help detect potential exploitation attempts. The fix addresses the core memory management issue by properly implementing reference counting and cleanup procedures within the associative array garbage collection mechanism, preventing the NULL pointer dereference conditions that previously occurred during concurrent key management operations.