In the Linux kernel, the following vulnerability has been resolved:
crypto: qat - fix DMA transfer direction
When CONFIG_DMA_API_DEBUG is selected, while running the crypto self
test on the QAT crypto algorithms, the function add_dma_entry() reports
a warning similar to the one below, saying that overlapping mappings
are not supported. This occurs in tests where the input and the output
scatter list point to the same buffers (i.e. two different scatter lists
which point to the same chunks of memory).
The logic that implements the mapping uses the flag DMA_BIDIRECTIONAL
for both the input and the output scatter lists which leads to
overlapped write mappings. These are not supported by the DMA layer.
Fix by specifying the correct DMA transfer directions when mapping
buffers. For in-place operations where the input scatter list
matches the output scatter list, buffers are mapped once with
DMA_BIDIRECTIONAL, otherwise input buffers are mapped using the flag
DMA_TO_DEVICE and output buffers are mapped with DMA_FROM_DEVICE.
Overlapping a read mapping with a write mapping is a valid case in
dma-coherent devices like QAT.
The function that frees and unmaps the buffers, qat_alg_free_bufl()
has been changed accordingly to the changes to the mapping function.
DMA-API: 4xxx 0000:06:00.0: cacheline tracking EEXIST, overlapping mappings aren't supported
WARNING: CPU: 53 PID: 4362 at kernel/dma/debug.c:570 add_dma_entry+0x1e9/0x270
...
Call Trace:
dma_map_page_attrs+0x82/0x2d0
? preempt_count_add+0x6a/0xa0
qat_alg_sgl_to_bufl+0x45b/0x990 [intel_qat]
qat_alg_aead_dec+0x71/0x250 [intel_qat]
crypto_aead_decrypt+0x3d/0x70
test_aead_vec_cfg+0x649/0x810
? number+0x310/0x3a0
? vsnprintf+0x2a3/0x550
? scnprintf+0x42/0x70
? valid_sg_divisions.constprop.0+0x86/0xa0
? test_aead_vec+0xdf/0x120
test_aead_vec+0xdf/0x120
alg_test_aead+0x185/0x400
alg_test+0x3d8/0x500
? crypto_acomp_scomp_free_ctx+0x30/0x30
? __schedule+0x32a/0x12a0
? ttwu_queue_wakelist+0xbf/0x110
? _raw_spin_unlock_irqrestore+0x23/0x40
? try_to_wake_up+0x83/0x570
? _raw_spin_unlock_irqrestore+0x23/0x40
? __set_cpus_allowed_ptr_locked+0xea/0x1b0
? crypto_acomp_scomp_free_ctx+0x30/0x30
cryptomgr_test+0x27/0x50
kthread+0xe6/0x110
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x1f/0x30
Publication date: Wed, 24 Dec 2025 13:06:00 +0000