CVE-2022-50774
Unknown Unknown - Not Provided
DMA Mapping Logic Flaw in Linux QAT Crypto Causes Overlapping Mappings

Publication date: 2025-12-24

Last updated on: 2025-12-24

Assigner: kernel.org

Description
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
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Meta Information
Published
2025-12-24
Last Modified
2025-12-24
Generated
2026-05-07
AI Q&A
2025-12-24
EPSS Evaluated
2026-05-05
NVD
CVE-2022-50774
EUVD
EUVD-2022-55787
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
intel qat *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability occurs in the Linux kernel's Intel QAT crypto driver when the DMA transfer directions are incorrectly specified during buffer mapping. Specifically, when the input and output scatter lists point to the same memory buffers, the driver uses the DMA_BIDIRECTIONAL flag for both, causing overlapping write mappings that are not supported by the DMA layer. This leads to warnings and potential issues during crypto self tests. The fix involves correctly specifying DMA transfer directions: using DMA_BIDIRECTIONAL for in-place operations where input and output buffers are the same, and using DMA_TO_DEVICE for input buffers and DMA_FROM_DEVICE for output buffers otherwise.


How can this vulnerability impact me? :

This vulnerability can cause warnings and errors during cryptographic operations using the Intel QAT driver in the Linux kernel, potentially leading to failed crypto self tests or unstable behavior when processing data buffers that overlap. It may affect the reliability and correctness of cryptographic operations relying on the QAT hardware acceleration.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by enabling CONFIG_DMA_API_DEBUG in the Linux kernel and running the crypto self test on the QAT crypto algorithms. When the issue occurs, the kernel logs a warning about overlapping mappings not being supported, similar to: 'DMA-API: 4xxx 0000:06:00.0: cacheline tracking EEXIST, overlapping mappings aren't supported' along with a stack trace involving add_dma_entry(). You can check the kernel logs (e.g., using 'dmesg' or 'journalctl -k') for such warnings. Running the command 'echo 1 > /sys/kernel/debug/dma_debug' may enable DMA debug messages if supported. Also, running the crypto self test for QAT modules can be done via the kernel self test framework or specific test utilities if available.


What immediate steps should I take to mitigate this vulnerability?

To mitigate this vulnerability, update the Linux kernel to a version where the fix is applied. The fix involves correcting the DMA transfer direction flags in the QAT crypto algorithms so that buffers are mapped with the correct DMA direction flags (DMA_BIDIRECTIONAL for in-place operations, DMA_TO_DEVICE for input buffers, and DMA_FROM_DEVICE for output buffers). This prevents overlapping write mappings that cause the warnings and potential issues. Until the update is applied, avoid running the crypto self tests with CONFIG_DMA_API_DEBUG enabled on QAT algorithms to prevent the warnings.


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