CVE-2024-46753 in Linux
Summary
by MITRE • 09/18/2024
In the Linux kernel, the following vulnerability has been resolved:
btrfs: handle errors from btrfs_dec_ref() properly
In walk_up_proc() we BUG_ON(ret) from btrfs_dec_ref(). This is incorrect, we have proper error handling here, return the error.
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Analysis
by VulDB Data Team • 04/05/2026
The vulnerability identified as CVE-2024-46753 resides within the Linux kernel's btrfs file system implementation and represents a critical error handling flaw that could lead to system instability and potential denial of service conditions. This issue specifically affects the btrfs file system's internal reference counting mechanism during directory traversal operations, where improper error handling can cause kernel panics and system crashes. The vulnerability manifests when the walk_up_proc() function encounters errors from the btrfs_dec_ref() function, which is responsible for decrementing reference counts on btrfs tree nodes and inodes during directory navigation.
The technical root cause of this vulnerability stems from an incorrect use of BUG_ON() macro within the walk_up_proc() function, which is designed to terminate execution immediately upon encountering an error condition. This approach violates proper kernel error handling conventions and creates a situation where legitimate error conditions from btrfs_dec_ref() are treated as kernel programming errors rather than recoverable system issues. The function btrfs_dec_ref() is a critical component in btrfs's reference counting system that manages the lifecycle of file system objects, and when it returns error codes indicating resource exhaustion, invalid state, or other failure conditions, these must be properly propagated and handled rather than triggering immediate kernel oops.
This flaw directly impacts system stability and availability by creating a path where normal file system operations can trigger kernel panics and system crashes. When btrfs_dec_ref() returns error codes during directory traversal operations, the improper error handling in walk_up_proc() causes the kernel to immediately terminate execution instead of gracefully handling the error condition. This behavior can be exploited by malicious actors to trigger denial of service conditions, particularly in environments where btrfs file systems are actively used for file operations, or by crafting specific file system access patterns that force the kernel into this error path. The vulnerability affects systems running Linux kernels with btrfs file system support, particularly those handling high volumes of directory traversal operations or systems where btrfs is the primary file system.
The operational impact of CVE-2024-46753 extends beyond simple system crashes to include potential data integrity concerns and service disruption in production environments. Systems utilizing btrfs file systems for critical operations such as database servers, storage appliances, or high-availability clusters could experience unexpected downtime when this vulnerability is triggered through normal file system operations. The error handling mechanism's failure to properly propagate errors means that legitimate system conditions can cause kernel panics rather than allowing the system to continue operating with appropriate error reporting. From a security perspective, this vulnerability could be leveraged in denial of service attacks against systems running affected kernel versions, potentially causing cascading failures in clustered or distributed environments where btrfs file systems are prevalent.
Mitigation strategies for this vulnerability should focus on immediate kernel updates to versions that contain the proper error handling fix, which addresses the incorrect BUG_ON() usage and implements appropriate error propagation from btrfs_dec_ref() calls. Organizations should prioritize patching affected systems, particularly those running btrfs file systems in production environments where system stability is critical. System administrators should monitor for kernel panic events and implement proper logging to detect potential exploitation attempts. The fix aligns with established kernel security practices and follows the principle of proper error handling as outlined in security standards such as those referenced in CWE-755 and ATT&CK techniques related to kernel exploitation and system stability compromise. Additionally, implementing proper monitoring and alerting for kernel oops conditions can help detect exploitation attempts before they cause significant system disruption, while maintaining regular kernel update schedules ensures protection against similar vulnerabilities in the future.