CVE-2023-54264 in Linux
Summary
by MITRE • 12/30/2025
In the Linux kernel, the following vulnerability has been resolved:
fs/sysv: Null check to prevent null-ptr-deref bug
sb_getblk(inode->i_sb, parent) return a null ptr and taking lock on that leads to the null-ptr-deref bug.
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Analysis
by VulDB Data Team • 04/27/2026
The vulnerability identified as CVE-2023-54264 resides within the Linux kernel's SysV filesystem implementation, specifically addressing a critical null pointer dereference issue that could potentially lead to system instability or privilege escalation. This flaw manifests in the filesystem's handling of block allocation operations where the function sb_getblk(inode->i_sb, parent) can return a null pointer under certain conditions. The null pointer return occurs when the system attempts to allocate or retrieve a block from the superblock associated with a parent inode, creating a scenario where subsequent operations attempt to access memory through a null reference.
The technical execution of this vulnerability involves the kernel's filesystem subsystem where the SysV filesystem driver fails to properly validate the return value from sb_getblk function before proceeding with lock operations. When the function returns null, indicating that block allocation failed or was not possible, the code continues to attempt locking operations on this null reference. This behavior constitutes a classic null pointer dereference vulnerability that violates fundamental memory safety principles and can be exploited by malicious actors to cause system crashes or potentially gain elevated privileges.
From an operational perspective, this vulnerability represents a significant risk to Linux systems utilizing SysV filesystems, particularly in environments where filesystem operations are frequent or where the system's stability is paramount. The null pointer dereference can result in kernel oops, system crashes, or denial of service conditions that may require system restarts to recover from. The impact extends beyond simple system instability as the vulnerability could potentially be leveraged in more sophisticated attacks targeting kernel memory management or privilege escalation scenarios.
The vulnerability aligns with CWE-476 which specifically addresses null pointer dereference issues in software implementations. This classification indicates that the flaw represents a common but dangerous programming error where developers fail to check for null return values before using pointers. The issue also relates to ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation' and T1499 which covers 'Endpoint Denial of Service' as the vulnerability could be exploited to either escalate privileges or cause system unavailability.
Mitigation strategies for CVE-2023-54264 involve applying the official kernel patch that implements proper null pointer validation before lock operations are performed. System administrators should prioritize updating their Linux kernel installations to versions containing the fix, particularly in production environments where SysV filesystems are in use. Additional defensive measures include monitoring system logs for kernel oops messages or unexpected crashes that might indicate exploitation attempts, implementing proper access controls to limit filesystem operations that could trigger the vulnerability, and maintaining regular kernel update schedules to address similar issues proactively. The patch implementation should be tested in staging environments before deployment to ensure compatibility with existing system configurations and applications.