Linux Kernel UBIFS Deadlock Vulnerability in Rename Whiteout and Inode Writeback Processes

A deadlock vulnerability has been identified in the Linux kernel's UBIFS file system, specifically during concurrent operations of renaming whiteout files and writing back inode data. This issue causes hung tasks as the rename process waits for the writeback to complete, while the writeback process is stalled, leading to a deadlock situation.

Impact

Exploitation of this vulnerability causes a deadlock, where tasks become unresponsive and unable to proceed, potentially leading to a system hang.

Reproduction

The vulnerability can be reproduced by using the SYS_renameat2 system call to rename a file to a whiteout name, while simultaneously consuming all available space to disrupt the writeback process. This creates a deadlock as the rename operation waits for the writeback to finish, but the writeback is blocked by the renamed whiteout.

Remediation

The vulnerability has been addressed in the official Linux Git repository. Users should upgrade to the latest version.