CVE-2023-53403 in Linux
Summary
by MITRE • 09/18/2025
In the Linux kernel, the following vulnerability has been resolved:
time/debug: Fix memory leak with using debugfs_lookup()
When calling debugfs_lookup() the result must have dput() called on it, otherwise the memory will leak over time. To make things simpler, just call debugfs_lookup_and_remove() instead which handles all of the logic at once.
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Analysis
by VulDB Data Team • 12/13/2025
The vulnerability identified as CVE-2023-53403 represents a memory management issue within the Linux kernel's debugfs subsystem that manifests as a gradual memory leak. This flaw specifically affects the time debugging functionality and occurs when the debugfs_lookup() function is invoked without proper cleanup operations. The issue stems from the kernel's debug filesystem implementation where references to debugfs entries are not properly released, leading to accumulated memory consumption over time. The vulnerability affects systems utilizing the Linux kernel's debugfs interface for time-related debugging operations, potentially impacting system stability and performance through unbounded memory growth.
The technical root cause of this vulnerability resides in improper resource management within the kernel's debugfs subsystem. When debugfs_lookup() is called to locate a debugfs entry, it returns a reference to the corresponding dentry structure that must be explicitly released using dput(). Failure to invoke dput() on the returned reference results in reference counting issues where the kernel cannot properly reclaim the memory associated with the debugfs entry. This memory leak occurs incrementally with each invocation of debugfs_lookup() without proper cleanup, creating a gradual degradation of system resources. The vulnerability is classified under CWE-404, which specifically addresses improper resource management and memory leaks in software systems.
The operational impact of this memory leak extends beyond simple resource consumption, potentially affecting system reliability and performance over extended periods of operation. As the memory leak accumulates, it can contribute to system slowdowns, increased swap usage, and eventually system instability or crashes when memory resources become critically constrained. Systems that frequently utilize debugfs_lookup() operations for time debugging purposes are particularly vulnerable, including those running kernel versions where this specific memory management flaw exists. The leak may be particularly problematic in embedded systems or servers operating continuously where memory conservation is critical for maintaining system uptime and performance.
The recommended mitigation strategy involves implementing the use of debugfs_lookup_and_remove() instead of the vulnerable debugfs_lookup() function, as this alternative handles all necessary cleanup operations automatically. This approach aligns with the principle of least privilege and proper resource management as outlined in secure coding practices and kernel development standards. System administrators should prioritize updating to kernel versions that contain the fix for CVE-2023-53403, which typically involves applying the relevant security patch that implements the recommended function replacement. Additionally, monitoring memory usage patterns and implementing automated alerting for memory consumption thresholds can help detect and mitigate the effects of this vulnerability in environments where immediate patching is not immediately feasible. The fix addresses the underlying issue by ensuring that all debugfs entry references are properly managed and released, preventing the accumulation of unreferenced memory structures that would otherwise persist in the kernel's memory management system.