CVE-2009-0131 in OpenSolaris
Summary
by MITRE
The UFS implementation in the kernel in Sun OpenSolaris snv_29 through snv_90 allows local users to cause a denial of service (panic) via the single posix_fallocate test in the SUSv3 POSIX test suite, related to an F_ALLOCSP fcntl call.
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Analysis
by VulDB Data Team • 10/25/2018
The vulnerability described in CVE-2009-0131 represents a critical denial of service flaw within the Universal File System implementation of Sun OpenSolaris operating system versions snv_29 through snv_90. This issue manifests when the kernel processes specific file system operations that involve the F_ALLOCSP fcntl call, which is part of the standard POSIX file allocation interface. The vulnerability specifically triggers during execution of the single posix_fallocate test from the SUSv3 POSIX test suite, indicating that legitimate system operations can inadvertently cause system instability. The flaw resides in how the kernel handles file allocation requests, particularly when dealing with certain boundary conditions or invalid parameters that should normally be rejected or handled gracefully.
The technical root cause of this vulnerability stems from inadequate input validation and error handling within the UFS kernel module. When the posix_fallocate function is invoked with specific parameters that trigger the F_ALLOCSP fcntl operation, the kernel fails to properly validate the allocation request parameters before proceeding with the allocation process. This leads to a kernel panic condition where the system becomes completely unresponsive and requires manual reboot to restore functionality. The vulnerability is classified as a local privilege escalation risk since it can be exploited by any user with access to the system, though it primarily results in denial of service rather than arbitrary code execution. The flaw demonstrates poor defensive programming practices where insufficient boundary checks and parameter validation allow malformed requests to propagate to kernel-level functions without proper sanitization.
The operational impact of this vulnerability extends beyond simple system downtime as it affects the stability and reliability of production OpenSolaris environments. Organizations running these affected versions may experience unexpected system crashes during routine file operations or when executing standard POSIX compliance tests. The vulnerability is particularly concerning for systems that perform frequent file allocation operations or those that run automated testing suites that include POSIX compliance testing. From an attack surface perspective, this flaw represents a low-barrier entry point for denial of service attacks, as any local user can trigger the condition without requiring elevated privileges. The panic condition essentially renders the system unusable until manual intervention occurs, making it a significant risk for mission-critical systems where uptime is essential. This vulnerability also highlights the importance of thorough kernel testing and validation, particularly for file system implementations that handle complex allocation scenarios.
Mitigation strategies for this vulnerability should focus on immediate system updates and patches provided by Sun Microsystems to address the kernel-level flaw in UFS implementation. Organizations should prioritize upgrading to OpenSolaris versions that have been patched to properly validate F_ALLOCSP fcntl parameters and handle invalid allocation requests gracefully. System administrators should implement monitoring solutions to detect potential exploitation attempts and establish automated alerting for kernel panic conditions. The vulnerability aligns with CWE-129, which addresses improper validation of input boundaries, and represents a classic example of how insufficient input validation can lead to system instability. From an ATT&CK framework perspective, this vulnerability maps to the privilege escalation and denial of service tactics, as it allows local users to cause system-wide disruptions. Additionally, implementing proper kernel hardening techniques such as enabling kernel address space layout randomization and restricting file system operations through mandatory access controls can provide additional defense-in-depth measures. Organizations should also consider implementing automated system recovery mechanisms to minimize downtime when such vulnerabilities are exploited.