CVE-2003-0465 in Linux
Summary
by MITRE
The kernel strncpy function in Linux 2.4 and 2.5 does not %NUL pad the buffer on architectures other than x86, as opposed to the expected behavior of strncpy as implemented in libc, which could lead to information leaks.
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Analysis
by VulDB Data Team • 05/25/2019
The vulnerability described in CVE-2003-0465 represents a critical inconsistency in the Linux kernel's implementation of the strncpy function across different processor architectures. This issue affects kernel versions 2.4 and 2.5, where the strncpy function fails to properly null-terminate buffers on non-x86 architectures, creating a deviation from the standard libc implementation that userspace applications expect. The root cause lies in the kernel's handling of string operations that differ significantly from userspace behavior, particularly when dealing with buffer boundaries and termination sequences.
This technical flaw manifests as an information disclosure vulnerability because when the kernel's strncpy implementation does not null-pad buffers on architectures such as arm, mips, or sparc, it leaves residual data from previous operations in memory. The inconsistency becomes particularly problematic when kernel code interacts with userspace applications that rely on proper string termination, creating potential attack vectors where malicious actors could exploit the memory layout to extract sensitive information. The vulnerability operates at the kernel level, making it particularly dangerous as it can be leveraged by local attackers or potentially remote attackers in specific scenarios where kernel memory is accessible.
The operational impact of this vulnerability extends beyond simple information leakage, as it can enable more sophisticated attacks including privilege escalation attempts and system compromise. When applications or kernel modules expect null-terminated strings but receive buffers with trailing garbage data, it can lead to unexpected behavior in string processing functions, potentially causing buffer overflows, format string vulnerabilities, or other memory corruption issues. This type of vulnerability aligns with CWE-121, which addresses buffer overflow conditions, and represents a classic example of how kernel-level inconsistencies can create security weaknesses. The attack surface is particularly concerning because it affects the fundamental string handling mechanisms that underpin numerous kernel operations and device drivers.
Mitigation strategies for this vulnerability require careful attention to kernel version management and architectural considerations. System administrators should prioritize upgrading to patched kernel versions where the strncpy implementation has been corrected to maintain consistent behavior across all supported architectures. The fix typically involves ensuring that kernel string functions properly null-terminate buffers regardless of the underlying architecture, aligning kernel behavior with the expected libc standards. Additionally, security monitoring should focus on detecting unusual memory access patterns and string processing anomalies that might indicate exploitation attempts. Organizations should implement comprehensive patch management policies specifically targeting kernel-level vulnerabilities and consider architectural-specific testing to verify that string handling functions behave consistently across all supported platforms. This vulnerability demonstrates the critical importance of maintaining consistency between kernel and userspace implementations, particularly for fundamental operations that handle memory and string data, as inconsistencies can create exploitable conditions that undermine system security.