CVE-2022-49995: writeback: avoid use-after-free after removing device

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-06-18 · updated 2026-08-04
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: writeback: avoid use-after-free after removing device When a disk is removed, bdi_unregister gets called to stop further writeback and wait for associated delayed work to complete. However, wb_inode_writeback_end() may schedule bandwidth estimation dwork after this has completed, which can result in the timer attempting to access the just freed bdi_writeback. Fix this by checking if the bdi_writeback is alive, similar to when scheduling writeback work. Since this requires wb->work_lock, and wb_inode_writeback_end() may get called from interrupt, switch wb->work_lock to an irqsafe lock.

Affected products

Linux kernel: from 5.15 before 5.15.64; from 5.16 before 5.19.6; 6.0-rc1, 6.0-rc2 — fixed in 5.15.64, 5.19.6

How to fix

Upgrade to a fixed version: Linux kernel 5.15.64, 5.19.6. Check the vendor advisory for mitigations.

References

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