CVE-2022-49469 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
btrfs: fix anon_dev leak in create_subvol()
When btrfs_qgroup_inherit(), btrfs_alloc_tree_block, or btrfs_insert_root() fail in create_subvol(), we return without freeing anon_dev. Reorganize the error handling in create_subvol() to fix this.
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Analysis
by VulDB Data Team • 10/23/2025
The vulnerability identified as CVE-2022-49469 represents a memory leak issue within the Linux kernel's btrfs filesystem implementation that specifically affects the create_subvol() function. This flaw manifests as an anonymous device (anon_dev) leak that occurs during the subvolume creation process when certain internal functions fail. The btrfs filesystem, which is a copy-on-write filesystem designed for Linux systems, implements various mechanisms for managing filesystem structures including quota groups and tree blocks. When the btrfs_qgroup_inherit(), btrfs_alloc_tree_block, or btrfs_insert_root() functions encounter failures during subvolume creation, the system does not properly clean up allocated anonymous device resources, leading to resource leakage.
The technical nature of this vulnerability stems from inadequate error handling within the create_subvol() function's control flow. The btrfs filesystem employs complex internal mechanisms for managing filesystem metadata and structures, where anonymous devices serve as temporary storage mechanisms for various filesystem operations. When these operations fail, the proper cleanup sequence that should release anonymous device resources is bypassed due to early returns from the function. This represents a classic resource management flaw where allocated resources are not properly deallocated in error paths, violating fundamental principles of memory management and resource cleanup. The vulnerability is classified as a memory leak under CWE-401 and specifically relates to improper cleanup of allocated resources during error conditions.
The operational impact of this vulnerability extends beyond simple memory consumption issues, as persistent resource leaks can lead to system instability and performance degradation over time. In environments where frequent subvolume creation and deletion operations occur, such as containerized environments or automated backup systems, the cumulative effect of these leaks can result in significant resource exhaustion. The leak affects the btrfs filesystem's ability to efficiently manage its internal resources, potentially leading to system resource exhaustion that could impact other filesystem operations or even cause system instability. This vulnerability particularly affects systems running Linux kernels with btrfs filesystem support, where the create_subvol() function is actively used for subvolume management operations.
Mitigation strategies for this vulnerability involve applying the kernel patch that reorganizes error handling within the create_subvol() function to ensure proper cleanup of anonymous device resources regardless of execution path. System administrators should prioritize updating their Linux kernel installations to versions that include the fix for CVE-2022-49469, as this addresses the root cause of the resource leak. The fix implements proper error handling mechanisms that guarantee anonymous device cleanup even when internal btrfs functions fail, aligning with ATT&CK technique T1484 which addresses privilege escalation through system resource manipulation. Organizations should also implement monitoring for memory usage patterns and resource consumption in systems utilizing btrfs filesystems to detect potential impacts from resource leaks. Regular kernel updates and security patch management processes should be maintained to ensure protection against similar vulnerabilities in the filesystem layer. The vulnerability demonstrates the importance of comprehensive error handling in kernel subsystems and highlights how seemingly isolated failures can lead to broader system resource management issues.