Linux Kernel Padata Parallel Processing Deadlock Vulnerability

A deadlock vulnerability has been identified in the Linux kernel's padata subsystem, specifically in the handling of parallel processing. This issue arises when an overloaded system executes parallel tasks in the current context, leaving bottom halves (BHs) enabled. The problem occurs in the padata_do_serial function, where BHs should be disabled to prevent interference from interrupts. The vulnerability affects the Linux kernel stable tree and has been addressed in a recent commit.

Impact

Exploitation of this vulnerability can lead to a deadlock situation, where the system becomes unresponsive due to conflicting processes waiting on each other.

Reproduction

The vulnerability can be reproduced by running an overloaded system that executes parallel tasks using the padata subsystem. This can be done by applying a workload that exceeds the system's processing capacity, causing the padata_do_parallel function to activate parallel processing while BHs remain enabled. As a result, interrupts can disrupt the padata_do_serial function, leading to a deadlock by causing it to wait indefinitely on a lock that is never released.

Remediation

Users can upgrade to the patched version of the Linux kernel available in the Linux kernel Git repository to address this vulnerability.