CVE-2017-18203 in Linux
Summary
by MITRE
The dm_get_from_kobject function in drivers/md/dm.c in the Linux kernel before 4.14.3 allow local users to cause a denial of service (BUG) by leveraging a race condition with __dm_destroy during creation and removal of DM devices.
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Analysis
by VulDB Data Team • 09/14/2025
The vulnerability identified as CVE-2017-18203 represents a critical race condition flaw within the Linux kernel's device mapper subsystem that affects versions prior to 4.14.3. This issue resides in the dm_get_from_kobject function located in drivers/md/dm.c, which governs the management of device mapper devices. The vulnerability arises from insufficient synchronization mechanisms during the concurrent creation and destruction of device mapper devices, creating a window where malicious local users can exploit temporal inconsistencies in the kernel's device management logic.
The technical exploitation of this vulnerability occurs through a carefully orchestrated race condition between the dm_get_from_kobject function and the __dm_destroy function during the lifecycle management of device mapper devices. When a local user creates and immediately destroys device mapper devices in rapid succession, the kernel's locking mechanisms fail to prevent concurrent access to shared data structures. This race condition can lead to a kernel BUG message being triggered, which results in a system crash or denial of service condition. The flaw specifically manifests when the kernel attempts to access device mapper objects that have been partially destroyed or are in an inconsistent state due to the timing of concurrent operations.
From an operational impact perspective, this vulnerability poses significant risks to system stability and availability, particularly in environments where device mapper functionality is heavily utilized. The local privilege escalation potential, while not directly allowing privilege elevation, creates a reliable method for causing system-wide disruption through denial of service attacks. Attackers can repeatedly trigger the race condition to destabilize systems running vulnerable kernel versions, potentially affecting critical infrastructure, virtualization platforms, and containerized environments that depend on device mapper functionality for storage management operations. The vulnerability affects systems across various deployment scenarios including servers, desktops, and embedded systems where the Linux kernel's device mapper subsystem is actively used.
The root cause of this vulnerability aligns with CWE-362, which describes a race condition error in software development where multiple threads or processes access shared resources concurrently without proper synchronization. This weakness creates opportunities for attackers to manipulate the timing of operations to achieve unintended behavior. The vulnerability also maps to ATT&CK technique T1499.001, which involves network denial of service attacks, although in this case the attack vector is local rather than network-based. Organizations should implement immediate mitigation strategies including kernel updates to version 4.14.3 or later, which contain the necessary synchronization fixes to prevent the race condition from being exploited. Additionally, system administrators should monitor for unusual patterns of device mapper activity and consider implementing access controls to limit local user capabilities that could trigger such conditions. The patch addresses the underlying synchronization issues by ensuring proper locking mechanisms are in place during device creation and destruction phases, preventing the inconsistent state that leads to the kernel BUG condition.