Early Access — Mondoo Vulnerability Intelligence is currently in preview.
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.