CVE-2005-0736 in Linux
Summary
by MITRE
Integer overflow in sys_epoll_wait in eventpoll.c for Linux kernel 2.6 to 2.6.11 allows local users to overwrite kernel memory via a large number of events.
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Analysis
by VulDB Data Team • 12/30/2024
The vulnerability identified as CVE-2005-0736 represents a critical integer overflow condition within the Linux kernel's event handling subsystem, specifically affecting kernel versions 2.6 through 2.6.11. This flaw exists in the sys_epoll_wait function located in the eventpoll.c file, which is responsible for managing epoll file descriptor operations that allow efficient I/O multiplexing. The vulnerability arises when a local user process attempts to register a large number of events with an epoll instance, causing the kernel to mishandle the integer arithmetic during event counting and memory allocation calculations.
The technical implementation of this vulnerability stems from improper input validation and arithmetic handling within the kernel's event processing logic. When a user process calls epoll_wait with an excessive number of events, the kernel's internal counter variables overflow beyond their maximum representable values, leading to incorrect memory calculations. This integer overflow condition results in the kernel allocating insufficient memory buffers while simultaneously attempting to write data beyond these boundaries, creating a classic buffer overflow scenario in kernel space. The flaw is particularly dangerous because it operates within kernel memory space, bypassing typical user-space memory protection mechanisms and allowing for arbitrary memory corruption.
The operational impact of CVE-2005-0736 is severe and multifaceted, as it provides local attackers with the capability to overwrite arbitrary kernel memory locations. This memory corruption can lead to system instability, potential privilege escalation, or even complete system compromise depending on the specific memory regions overwritten. Attackers can leverage this vulnerability to execute arbitrary code within kernel context, potentially gaining root privileges or causing denial of service conditions that could bring the entire system to a halt. The vulnerability affects all Linux systems running kernel versions in the specified range, making it a widespread concern for system administrators and security professionals managing these older kernel versions.
This vulnerability aligns with CWE-190, which classifies integer overflow conditions, and represents a classic example of how improper integer handling in kernel code can create exploitable security weaknesses. From an attack framework perspective, this vulnerability maps to the privilege escalation and denial of service techniques documented in the MITRE ATT&CK framework, specifically targeting the kernel memory space and system stability. The exploitability of this vulnerability is enhanced by the fact that it requires only local user access, making it particularly dangerous in multi-user environments where untrusted users might have access to system resources. System administrators should prioritize updating affected kernel versions to prevent exploitation, as the vulnerability cannot be mitigated through network-level defenses due to its local execution requirement. The fix typically involves proper integer overflow checking and bounds validation in the eventpoll.c implementation to ensure that event counts and memory allocations remain within safe operational limits.