Linux Kernel ext4 Deadlock Vulnerability in Inline Directory Conversion

A deadlock vulnerability has been identified in the Linux kernel's ext4 file system, specifically when converting inline directories in no journal mode. The issue arises in the function ext4_finish_convert_inline_dir(), which can self-deadlock by calling ext4_handle_dirty_dirblock() while already holding the directory lock. A similar deadlock occurs in ext4_convert_inline_data_nolock() for data files. This vulnerability affects the Linux kernel ext4 file system in no journal mode.

Impact

Exploitation of this vulnerability leads to a self-imposed deadlock, causing the system to hang indefinitely while attempting to resolve the lock contention.

Reproduction

The vulnerability can be reproduced by creating an ext2 file system with inline data support, mounting it as ext4 with directory synchronization, and then manipulating files in a way that triggers the deadlock during the inline directory conversion process.

Remediation

Users can upgrade to the latest version of the Linux kernel where this vulnerability has been addressed.