TLDRVuln - Cybersecurity Vulnerabilities Made Simple

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

IB/core: Fix a nested dead lock as part of ODP flow

Fix a nested dead lock as part of ODP flow by using mmput_async().

From the below call trace [1] can see that calling mmput() once we have

the umem_odp->umem_mutex locked as required by

ib_umem_odp_map_dma_and_lock() might trigger in the same task the

exit_mmap()->__mmu_notifier_release()->mlx5_ib_invalidate_range() which

may dead lock when trying to lock the same mutex.

Moving to use mmput_async() will solve the problem as the above

exit_mmap() flow will be called in other task and will be executed once

the lock will be available.

[1]

[64843.077665] task:kworker/u133:2 state:D stack: 0 pid:80906 ppid:

2 flags:0x00004000

[64843.077672] Workqueue: mlx5_ib_page_fault mlx5_ib_eqe_pf_action [mlx5_ib]

[64843.077719] Call Trace:

[64843.077722] <TASK>

[64843.077724] __schedule+0x23d/0x590

[64843.077729] schedule+0x4e/0xb0

[64843.077735] schedule_preempt_disabled+0xe/0x10

[64843.077740] __mutex_lock.constprop.0+0x263/0x490

[64843.077747] __mutex_lock_slowpath+0x13/0x20

[64843.077752] mutex_lock+0x34/0x40

[64843.077758] mlx5_ib_invalidate_range+0x48/0x270 [mlx5_ib]

[64843.077808] __mmu_notifier_release+0x1a4/0x200

[64843.077816] exit_mmap+0x1bc/0x200

[64843.077822] ? walk_page_range+0x9c/0x120

[64843.077828] ? __cond_resched+0x1a/0x50

[64843.077833] ? mutex_lock+0x13/0x40

[64843.077839] ? uprobe_clear_state+0xac/0x120

[64843.077860] mmput+0x5f/0x140

[64843.077867] ib_umem_odp_map_dma_and_lock+0x21b/0x580 [ib_core]

[64843.077931] pagefault_real_mr+0x9a/0x140 [mlx5_ib]

[64843.077962] pagefault_mr+0xb4/0x550 [mlx5_ib]

[64843.077992] pagefault_single_data_segment.constprop.0+0x2ac/0x560

[mlx5_ib]

[64843.078022] mlx5_ib_eqe_pf_action+0x528/0x780 [mlx5_ib]

[64843.078051] process_one_work+0x22b/0x3d0

[64843.078059] worker_thread+0x53/0x410

[64843.078065] ? process_one_work+0x3d0/0x3d0

[64843.078073] kthread+0x12a/0x150

[64843.078079] ? set_kthread_struct+0x50/0x50

[64843.078085] ret_from_fork+0x22/0x30

[64843.078093] </TASK>