Linux Kernel Btrfs Component Sleep Vulnerability in Atomic Context

A vulnerability exists in the Linux kernel's Btrfs file system component, specifically within the trace event 'btrfs_sync_file()'. This event is executed in an atomic context, where certain operations that can sleep are not permitted. The issue arises because 'btrfs_sync_file()' calls 'dput()', needed for 'dget_parent()', which can sleep and disrupt the atomic context, causing a kernel warning. This vulnerability can be reproduced by enabling the 'btrfs_sync_file' trace event and running the 'btrfs/056' test from the 'fstests' suite. The resulting kernel warning indicates that a sleeping function was called from an invalid context, violating the requirements for atomic operations.

Impact

Exploitation of this vulnerability leads to a kernel warning, indicating a violation of atomic context requirements, which could potentially be exploited to cause a denial of service by disrupting normal kernel operations.

Reproduction

To reproduce this vulnerability, enable the 'btrfs_sync_file' trace event and execute the 'btrfs/056' test from the 'fstests' suite. The vulnerability manifests as a kernel warning in the 'dmesg' log, indicating that a sleeping function was called from an invalid context, which is not allowed in atomic operations.

Remediation

The vulnerability has been addressed in the Linux kernel. Users should upgrade to the latest version where this issue has been fixed.