CVE-2022-48658

In the Linux kernel, the following vulnerability has been resolved:

mm: slub: fix flush_cpu_slab()/__free_slab() invocations in task context.

Commit 5a836bf6b09f ("mm: slub: move flush_cpu_slab() invocations

__free_slab() invocations out of IRQ context") moved all flush_cpu_slab()

invocations to the global workqueue to avoid a problem related

with deactivate_slab()/__free_slab() being called from an IRQ context

on PREEMPT_RT kernels.

When the flush_all_cpu_locked() function is called from a task context

it may happen that a workqueue with WQ_MEM_RECLAIM bit set ends up

flushing the global workqueue, this will cause a dependency issue.

workqueue: WQ_MEM_RECLAIM nvme-delete-wq:nvme_delete_ctrl_work [nvme_core]

is flushing !WQ_MEM_RECLAIM events:flush_cpu_slab

WARNING: CPU: 37 PID: 410 at kernel/workqueue.c:2637

check_flush_dependency+0x10a/0x120

Workqueue: nvme-delete-wq nvme_delete_ctrl_work [nvme_core]

RIP: 0010:check_flush_dependency+0x10a/0x120[ 453.262125] Call Trace:

__flush_work.isra.0+0xbf/0x220

? __queue_work+0x1dc/0x420

flush_all_cpus_locked+0xfb/0x120

__kmem_cache_shutdown+0x2b/0x320

kmem_cache_destroy+0x49/0x100

bioset_exit+0x143/0x190

blk_release_queue+0xb9/0x100

kobject_cleanup+0x37/0x130

nvme_fc_ctrl_free+0xc6/0x150 [nvme_fc]

nvme_free_ctrl+0x1ac/0x2b0 [nvme_core]

Fix this bug by creating a workqueue for the flush operation with

the WQ_MEM_RECLAIM bit set.