CVE-2024-46841 in Linux
Summary
by MITRE • 09/27/2024
In the Linux kernel, the following vulnerability has been resolved:
btrfs: don't BUG_ON on ENOMEM from btrfs_lookup_extent_info() in walk_down_proc()
We handle errors here properly, ENOMEM isn't fatal, return the error.
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Analysis
by VulDB Data Team • 04/05/2026
The vulnerability identified as CVE-2024-46841 affects the Linux kernel's btrfs file system implementation and represents a critical issue in error handling mechanisms. This flaw exists within the walk_down_proc() function where the kernel incorrectly uses BUG_ON() macro when encountering ENOMEM errors from the btrfs_lookup_extent_info() function. The BUG_ON() macro is designed to trigger kernel panics when unrecoverable conditions occur, but ENOMEM errors are not fatal conditions that should cause system crashes. This improper error handling stems from a misunderstanding of error semantics within the btrfs subsystem where memory allocation failures are expected and should be handled gracefully rather than causing system-wide failures.
The technical nature of this vulnerability aligns with CWE-704, which describes incorrect error handling in kernel space, and specifically relates to improper handling of out-of-memory conditions. When btrfs_lookup_extent_info() returns ENOMEM, it indicates that the system has exhausted available memory for a specific operation, but this does not represent a fundamental system failure that requires immediate kernel panic. The function walk_down_proc() currently treats this recoverable error condition as if it were a fatal system error, leading to unnecessary system crashes that could be prevented through proper error propagation. This error handling pattern violates the principle of graceful degradation where systems should continue operating or fail gracefully rather than crashing entirely.
The operational impact of this vulnerability extends beyond simple system instability to potentially disrupt critical infrastructure operations that rely on btrfs file systems. When a system encounters this condition, particularly during intensive file system operations or memory pressure scenarios, it will experience unexpected kernel panics and system crashes. This can lead to data loss, service interruptions, and potential denial of service conditions in environments where btrfs is the primary file system. The vulnerability is particularly concerning in high-availability systems, storage servers, and cloud infrastructure where such crashes could cascade into larger system failures. From an attacker perspective, this represents a potential denial of service vector that could be exploited to repeatedly crash systems running btrfs file systems.
Mitigation strategies for CVE-2024-46841 focus on updating to kernel versions that contain the fix, which properly handles ENOMEM errors by returning them instead of triggering kernel panics. System administrators should prioritize patching affected systems, particularly those running btrfs file systems under heavy memory pressure or high I/O loads. The fix aligns with ATT&CK technique T1499.004, which involves system disruption through kernel-level errors, but the mitigation approach addresses this by ensuring proper error propagation rather than allowing kernel panics. Organizations should also implement monitoring for system crashes and memory allocation failures to detect potential exploitation attempts. Additionally, system hardening measures including memory management tuning, proper resource allocation, and regular kernel updates should be maintained to prevent similar vulnerabilities from emerging in other parts of the kernel codebase. The fix demonstrates proper error handling practices that should be applied across kernel subsystems to prevent similar issues where recoverable errors are treated as fatal conditions.