CVE-2023-53292 in Linux
Summary
by MITRE • 09/16/2025
In the Linux kernel, the following vulnerability has been resolved:
blk-mq: fix NULL dereference on q->elevator in blk_mq_elv_switch_none
After grabbing q->sysfs_lock, q->elevator may become NULL because of elevator switch.
Fix the NULL dereference on q->elevator by checking it with lock.
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Analysis
by VulDB Data Team • 06/02/2026
The vulnerability identified as CVE-2023-53292 represents a critical NULL dereference issue within the Linux kernel's block multiqueue subsystem, specifically affecting the blk_mq_elv_switch_none function. This flaw exists in the kernel's storage I/O handling mechanism where the system attempts to access the elevator structure without proper validation of its existence. The block multiqueue subsystem manages I/O requests for storage devices and relies on elevator algorithms to optimize request scheduling, making this vulnerability particularly dangerous as it could disrupt fundamental storage operations.
The technical root cause stems from a race condition scenario where the kernel's locking mechanism fails to maintain consistency between the acquisition of q->sysfs_lock and the subsequent access to q->elevator. During the execution of blk_mq_elv_switch_none, the system first acquires the sysfs_lock to ensure thread safety for sysfs operations, but between this lock acquisition and the actual access to the elevator structure, another process or thread may have initiated an elevator switch operation. This elevator switch can result in the q->elevator pointer being set to NULL, creating a situation where the subsequent code attempts to dereference a null pointer, leading to a kernel panic or system crash.
This vulnerability directly relates to CWE-476 which defines NULL Pointer Dereference as a weakness where a null value is dereferenced as if it were a valid pointer, and it aligns with ATT&CK technique T1499.001 which involves network denial of service through system resource exhaustion. The impact of this flaw extends beyond simple system instability as it can lead to complete system crashes during I/O operations, particularly when the system is under load or when elevator switching operations are frequent. The vulnerability affects any Linux system running a kernel version that includes the problematic blk-mq implementation, making it a widespread concern across various server and desktop environments.
The operational implications of CVE-2023-53292 are severe, as it can cause systems to become unresponsive or crash entirely during normal I/O operations, particularly in environments with high storage I/O activity or systems that frequently switch elevator algorithms. This vulnerability essentially creates a window where the kernel's storage subsystem becomes unstable, potentially leading to data loss or service interruption in critical infrastructure. The flaw is particularly concerning in enterprise environments where storage reliability is paramount, as it could result in unplanned downtime and impact business continuity.
Mitigation strategies for this vulnerability primarily involve applying the official kernel patch that implements proper NULL checking before accessing the q->elevator pointer. The fix requires that developers ensure the elevator pointer is validated within the locked context before any dereference operations occur. Organizations should prioritize updating their kernel versions to include the patched implementation, typically found in kernel versions 6.3 and later. System administrators should also monitor for any unusual system crashes or I/O-related errors that might indicate exploitation attempts. Additionally, implementing proper system monitoring and alerting mechanisms can help detect potential exploitation attempts before they cause significant system instability, as the vulnerability's impact is most pronounced during active I/O operations.