CVE-2019-20423 in File System
Summary
by MITRE
In the Lustre file system before 2.12.3, the ptlrpc module has a buffer overflow and panic due to the lack of validation for specific fields of packets sent by a client. The function target_handle_connect() mishandles a certain size value when a client connects to a server, because of an integer signedness error.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 01/27/2020
The vulnerability identified as CVE-2019-20423 represents a critical buffer overflow condition within the Lustre distributed file system implementation, specifically affecting versions prior to 2.12.3. This flaw resides in the ptlrpc module, which serves as the primary communication layer between Lustre clients and servers. The vulnerability manifests when a client attempts to establish a connection with a Lustre server, creating a scenario where malicious or malformed packets can trigger system instability. The root cause stems from inadequate validation of packet fields, particularly those related to size parameters, which allows an attacker to manipulate the connection process and potentially cause system crashes.
The technical exploitation of this vulnerability occurs through a specific integer signedness error within the target_handle_connect() function. This function processes connection requests from clients and fails to properly validate the size field contained within incoming packets. When a client sends a packet with an unexpectedly large or negative size value, the function incorrectly interprets this value due to the signedness mismatch, leading to an improper buffer allocation. The integer signedness error creates a condition where a 32-bit unsigned integer value is treated as a signed integer, allowing values that exceed the expected range to be processed incorrectly. This misinterpretation results in a buffer overflow scenario where the system attempts to allocate memory based on an invalid size parameter, ultimately causing a kernel panic and system crash.
The operational impact of CVE-2019-20423 extends beyond simple system instability, as it represents a denial-of-service vulnerability that can be exploited remotely without authentication. This makes it particularly dangerous in enterprise environments where Lustre file systems are deployed for high availability and mission-critical workloads. The vulnerability affects both client and server components, meaning that any system participating in a Lustre network could become compromised through a single malicious connection attempt. The panic condition triggered by this flaw can result in complete system shutdowns, data loss, and extended downtime for affected services. Organizations relying on Lustre for storage infrastructure face significant operational risks, as this vulnerability can be exploited by adversaries to disrupt services or potentially gain unauthorized access to network resources.
Security practitioners should implement immediate mitigations including updating to Lustre version 2.12.3 or later, which contains the necessary patches for this vulnerability. Network segmentation and access controls should be strengthened to limit client-server communication to trusted networks only. Monitoring should be enhanced to detect unusual connection patterns or malformed packets that may indicate exploitation attempts. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and can be mapped to ATT&CK technique T1499.001, which covers network denial-of-service attacks. Organizations should also consider implementing intrusion detection systems capable of identifying malformed Lustre protocol packets and establishing incident response procedures for handling potential exploitation attempts. Regular security assessments of Lustre implementations are essential to identify and remediate similar vulnerabilities in the broader storage infrastructure ecosystem.