Linux Kernel Vulnerability Affecting JBD2 Journal Functions

CVE-2025-39782

What is CVE-2025-39782?

A vulnerability in the Linux kernel's JBD2 journal functions has been identified, where improper management of the j_list_lock can lead to significant delays in processing. The functions jbd2_log_do_checkpoint() and jbd2_journal_shrink_checkpoint_list() release the j_list_lock after processing buffers, but the contention can result in prolonged wait times. Although jbd2_journal_shrink_checkpoint_list() includes measures to prevent soft lockups, jbd2_log_do_checkpoint() relies on potentially non-sleeping functions to trigger rescheduling, which can cause the kernel to experience soft lockups, leading to performance degradation and system instability.

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