Linux Kernel Race Condition Vulnerability in ext4 File System

A race condition vulnerability has been identified in the ext4 file system of the Linux kernel. This issue arises between the ext4_write and ext4_convert_inline_data functions, leading to a kernel BUG. The vulnerability can cause an inconsistency in the block bitmap and group descriptor, triggering a fatal error in the kernel. The race condition occurs because the ext4_convert_inline_data function holds a different lock than the one held by the generic_perform_write function, allowing for concurrent execution that can disrupt data integrity.

Impact

Exploitation of this vulnerability leads to a kernel panic, causing a crash of the affected system.

Reproduction

The vulnerability can be reproduced by performing a write operation on a file system that uses ext4. This can be done by writing data to a file while simultaneously executing a command that converts inline data for the same file. The race condition will cause the system to encounter a BUG_ON error, indicating a reference count issue with the journal handle, which is a sign of the race condition being exploited.

Remediation

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