CVE-2024-23850 in Linux
Summary
by MITRE • 01/23/2024
In btrfs_get_root_ref in fs/btrfs/disk-io.c in the Linux kernel through 6.7.1, there can be an assertion failure and crash because a subvolume can be read out too soon after its root item is inserted upon subvolume creation.
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Analysis
by VulDB Data Team • 02/11/2025
The vulnerability identified as CVE-2024-23850 represents a critical race condition within the btrfs filesystem implementation in the Linux kernel version 6.7.1 and earlier. This flaw exists in the btrfs_get_root_ref function located in fs/btrfs/disk-io.c, where the kernel fails to properly synchronize access to subvolume root items during the subvolume creation process. The issue arises from insufficient coordination between the insertion of root items and subsequent reading operations, creating a temporal window where a subvolume can be accessed prematurely before its internal data structures are fully initialized and consistent.
The technical implementation of this vulnerability stems from a fundamental flaw in the btrfs filesystem's metadata management system. When a new subvolume is created, the kernel inserts a root item into the filesystem's metadata structures, but the subsequent read operations that attempt to access this newly created subvolume can occur before the underlying data structures are properly committed to disk or made fully accessible to other kernel subsystems. This race condition manifests as an assertion failure, which ultimately leads to a system crash or kernel panic, effectively causing a denial of service condition that can render the entire system unstable.
From an operational perspective, this vulnerability presents a severe security risk as it can be exploited to cause system instability and potential denial of service attacks against systems running affected Linux kernel versions. The crash occurs during normal subvolume creation operations, meaning that any legitimate user or application attempting to create subvolumes can trigger this condition. The impact extends beyond simple service disruption as kernel panics can lead to data corruption, system restarts, and potentially provide attackers with opportunities to escalate privileges or gain unauthorized access to system resources. This vulnerability particularly affects systems heavily dependent on btrfs filesystem functionality, including enterprise storage solutions, cloud infrastructure, and containerized environments that rely on btrfs for their storage management.
The mitigation strategies for CVE-2024-23850 primarily involve upgrading to a patched version of the Linux kernel where this race condition has been resolved through proper synchronization mechanisms. System administrators should prioritize updating their kernel versions to ensure that the btrfs filesystem implementation includes appropriate locking mechanisms and temporal consistency checks during subvolume creation operations. Additionally, organizations should implement monitoring solutions to detect unusual subvolume creation patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-362, which describes a race condition in kernel-level filesystem operations, and could potentially be leveraged as part of broader attack chains that align with ATT&CK techniques involving privilege escalation and system stability compromise. Regular security audits of kernel components and filesystem operations should be conducted to identify similar race conditions that might exist in other subsystems.