NuytsTech Security

CVE-2024-47143

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

dma-debug: fix a possible deadlock on radix_lock

radix_lock() shouldn’t be held while holding dma_hash_entry[idx].lock
otherwise, there’s a possible deadlock scenario when
dma debug API is called holding rq_lock():

CPU0 CPU1 CPU2
dma_free_attrs()
check_unmap() add_dma_entry() __schedule() //out
(A) rq_lock()
get_hash_bucket()
(A) dma_entry_hash
check_sync()
(A) radix_lock() (W) dma_entry_hash
dma_entry_free()
(W) radix_lock()
// CPU2’s one
(W) rq_lock()

CPU1 situation can happen when it extending radix tree and
it tries to wake up kswapd via wake_all_kswapd().

CPU2 situation can happen while perf_event_task_sched_out()
(i.e. dma sync operation is called while deleting perf_event using
etm and etr tmc which are Arm Coresight hwtracing driver backends).

To remove this possible situation, call dma_entry_free() after
put_hash_bucket() in check_unmap().

More information : https://git.kernel.org/stable/c/3ccce34a5c3f5c9541108a451657ade621524b32

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