CVE-2022-49833 in Linux
Summary
by MITRE • 05/01/2025
In the Linux kernel, the following vulnerability has been resolved:
btrfs: zoned: clone zoned device info when cloning a device
When cloning a btrfs_device, we're not cloning the associated btrfs_zoned_device_info structure of the device in case of a zoned filesystem.
Later on this leads to a NULL pointer dereference when accessing the device's zone_info for instance when setting a zone as active.
This was uncovered by fstests' testcase btrfs/161.
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Analysis
by VulDB Data Team • 11/10/2025
The vulnerability identified as CVE-2022-49833 represents a critical flaw in the Linux kernel's btrfs filesystem implementation that specifically affects zoned storage devices. This issue stems from an incomplete implementation of device cloning operations within the btrfs subsystem, where the essential zoned device information structure is not properly duplicated when creating clones of btrfs_device objects. The root cause lies in the failure to maintain proper data consistency between parent and cloned device structures, particularly in environments utilizing zoned storage architectures such as those found in modern enterprise storage systems and cloud infrastructure.
The technical flaw manifests as a missing data structure cloning operation within the btrfs device management code path. When a btrfs_device is cloned, the associated btrfs_zoned_device_info structure that contains crucial zone management information is not duplicated, leaving the cloned device reference pointing to a NULL pointer. This particular implementation gap creates a dangerous state where subsequent operations attempting to access zone-related information through the cloned device will result in immediate system crashes due to NULL pointer dereference exceptions. The vulnerability specifically impacts zoned filesystem operations where zone management is critical for proper storage allocation and performance optimization.
The operational impact of this vulnerability extends beyond simple system crashes to potentially compromise data integrity and availability in production environments. When the system attempts to set a zone as active or perform any zone-related operations on a cloned device, the NULL pointer dereference causes kernel oops and system instability. This can lead to complete system panics, requiring manual intervention and system restarts, which is particularly problematic in mission-critical environments where uptime and data consistency are paramount. The vulnerability affects any system running btrfs filesystems on zoned storage devices, making it a significant concern for enterprise storage solutions and cloud providers utilizing such infrastructure.
The issue was discovered and validated through comprehensive testing using the fstests framework, specifically the btrfs/161 test case which exercises the cloning and zoned device management functionality. This testing methodology ensures that the vulnerability manifests under realistic operational conditions, demonstrating that the flaw is not merely theoretical but can be triggered by normal filesystem operations. The vulnerability aligns with CWE-476 which addresses NULL pointer dereference conditions, and represents a classic case of incomplete resource management in kernel space operations. From an attack perspective, this vulnerability could be exploited to cause denial of service attacks against systems running btrfs on zoned storage, potentially affecting availability and service continuity.
Mitigation strategies for this vulnerability include immediate application of kernel updates that contain the proper device structure cloning implementation, ensuring that btrfs_zoned_device_info structures are correctly duplicated during device cloning operations. System administrators should prioritize patching affected systems, particularly those running btrfs filesystems on zoned storage devices. Additionally, monitoring systems should be configured to detect kernel oops and system instability patterns that may indicate exploitation attempts. The fix addresses the underlying architectural issue by implementing proper deep copying of the zoned device information structure, ensuring that cloned btrfs_device objects maintain valid references to their associated zone management data. Organizations should also consider implementing redundancy measures and backup procedures to minimize impact from potential exploitation scenarios while awaiting patch deployment.