CVE-2023-53732 in Linux
Summary
by MITRE • 10/22/2025
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: Fix NULL dereference in ni_write_inode
Syzbot reports a NULL dereference in ni_write_inode. When creating a new inode, if allocation fails in mi_init function (called in mi_format_new function), mi->mrec is set to NULL. In the error path of this inode creation, mi->mrec is later dereferenced in ni_write_inode.
Add a NULL check to prevent NULL dereference.
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Analysis
by VulDB Data Team • 02/28/2026
The vulnerability described in CVE-2023-53732 represents a critical NULL pointer dereference flaw within the Linux kernel's ntfs3 filesystem driver. This issue manifests specifically in the ni_write_inode function where improper error handling leads to a system crash when attempting to write inode data to a newly created filesystem entry. The vulnerability stems from a race condition or allocation failure scenario that occurs during the initialization of metadata records within the NTFS3 filesystem implementation. The flaw is particularly dangerous because it can be triggered during normal filesystem operations, potentially leading to system instability or denial of service conditions.
The technical root cause of this vulnerability lies in the improper handling of memory allocation failures within the mi_init function, which is invoked during the mi_format_new function execution. When memory allocation fails during inode creation, the mi->mrec pointer is correctly set to NULL to indicate the failed allocation state. However, subsequent error handling code fails to account for this NULL state when calling ni_write_inode, resulting in a direct dereference of the NULL pointer. This pattern violates fundamental memory safety principles and creates an exploitable condition that can be leveraged to crash the kernel or potentially escalate privileges. The vulnerability aligns with CWE-476 which specifically addresses NULL pointer dereference conditions in software implementations.
The operational impact of this vulnerability extends beyond simple system crashes, as it can be exploited to create persistent denial of service conditions within systems running affected Linux kernel versions. Attackers could potentially trigger this condition through malicious filesystem operations or by exhausting system resources during normal file creation processes. The vulnerability affects systems that utilize NTFS3 filesystems and could be particularly impactful in enterprise environments where filesystem stability is critical. The null dereference occurs in kernel space, meaning successful exploitation could lead to complete system compromise or require system reboot to recover from the crash state.
Mitigation strategies for CVE-2023-53732 should prioritize immediate kernel updates from trusted sources to ensure the patched version resolves the NULL pointer dereference issue. System administrators should implement monitoring for filesystem-related kernel crashes and ensure regular patch management protocols are followed to maintain system security. The fix implemented in the patched kernel version involves adding a simple but crucial NULL pointer check before attempting to dereference the mi->mrec pointer in the ni_write_inode function. This defensive programming approach prevents the kernel from crashing when allocation failures occur during filesystem operations, thereby maintaining system stability and preventing potential exploitation. Organizations should also consider implementing additional filesystem monitoring and alerting mechanisms to detect unusual patterns that might indicate attempted exploitation of similar vulnerabilities. The vulnerability demonstrates the importance of proper error handling in kernel space operations and highlights the necessity of comprehensive testing for allocation failure scenarios in filesystem implementations.