CVE-2026-46077
Description
In the Linux kernel, the following vulnerability has been resolved:
crypto: atmel-tdes - fix DMA sync direction
Before DMA output is consumed by the CPU, ->dma_addr_out must be synced with dma_sync_single_for_cpu() instead of dma_sync_single_for_device(). Using the wrong direction can return stale cache data on non-coherent platforms.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
In Linux kernel's atmel-tdes driver, incorrect DMA sync direction can cause stale cache data on non-coherent platforms.
Vulnerability
The atmel-tdes driver in the Linux kernel used dma_sync_single_for_device() instead of dma_sync_single_for_cpu() when synchronizing DMA output buffers before CPU access. This bug affects non-coherent platforms where cache coherence is not maintained, potentially returning stale cached data. The issue is present in versions prior to the fix commit [1].
Exploitation
An attacker would need to trigger the use of the atmel-tdes cryptographic engine on a non-coherent system. No authentication or special privileges are required to trigger the vulnerable code path, as it is invoked during normal crypto operations. The specific sequence involves the driver performing a DMA transfer and then incorrectly syncing the buffer for device access instead of CPU access before reading the output.
Impact
On non-coherent platforms, the incorrect DMA sync direction can result in the CPU reading stale data from the cache instead of the actual DMA output. This could lead to information disclosure (e.g., leaking kernel memory) or incorrect cryptographic results, depending on how the output is used.
Mitigation
The vulnerability is fixed in Linux kernel commit 863d11b3927703ad95077c81a8a6489c5c7872f7 [1]. Users should apply the latest kernel updates. No workaround is available. The fix has been merged into the stable kernel tree.
AI Insight generated on May 27, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
1Patches
10c8a9a647532fcrypto: atmel-tdes - fix DMA sync direction
1 file changed · +4 −5
drivers/crypto/atmel-tdes.c+4 −5 modifieddiff --git a/drivers/crypto/atmel-tdes.c b/drivers/crypto/atmel-tdes.c index 278c0df3c92f26..643e507f9c0209 100644 --- a/drivers/crypto/atmel-tdes.c +++ b/drivers/crypto/atmel-tdes.c @@ -294,8 +294,8 @@ static int atmel_tdes_crypt_pdc_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, @@ -619,8 +619,8 @@ static int atmel_tdes_crypt_dma_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, -- cgit 1.3-korg
12a0adfe498ccrypto: atmel-tdes - fix DMA sync direction
1 file changed · +4 −5
drivers/crypto/atmel-tdes.c+4 −5 modifieddiff --git a/drivers/crypto/atmel-tdes.c b/drivers/crypto/atmel-tdes.c index d15b2e943447ef..813ed47e60cceb 100644 --- a/drivers/crypto/atmel-tdes.c +++ b/drivers/crypto/atmel-tdes.c @@ -294,8 +294,8 @@ static int atmel_tdes_crypt_pdc_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, @@ -619,8 +619,8 @@ static int atmel_tdes_crypt_dma_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, -- cgit 1.3-korg
b5f5df801d16crypto: atmel-tdes - fix DMA sync direction
1 file changed · +4 −5
drivers/crypto/atmel-tdes.c+4 −5 modifieddiff --git a/drivers/crypto/atmel-tdes.c b/drivers/crypto/atmel-tdes.c index 278c0df3c92f26..643e507f9c0209 100644 --- a/drivers/crypto/atmel-tdes.c +++ b/drivers/crypto/atmel-tdes.c @@ -294,8 +294,8 @@ static int atmel_tdes_crypt_pdc_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, @@ -619,8 +619,8 @@ static int atmel_tdes_crypt_dma_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, -- cgit 1.3-korg
5281e6e23023crypto: atmel-tdes - fix DMA sync direction
1 file changed · +4 −5
drivers/crypto/atmel-tdes.c+4 −5 modifieddiff --git a/drivers/crypto/atmel-tdes.c b/drivers/crypto/atmel-tdes.c index d234495f1115b8..6870a13342e22c 100644 --- a/drivers/crypto/atmel-tdes.c +++ b/drivers/crypto/atmel-tdes.c @@ -304,8 +304,8 @@ static int atmel_tdes_crypt_pdc_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, @@ -655,8 +655,8 @@ static int atmel_tdes_crypt_dma_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, -- cgit 1.3-korg
863d11b39277crypto: atmel-tdes - fix DMA sync direction
1 file changed · +4 −5
drivers/crypto/atmel-tdes.c+4 −5 modifieddiff --git a/drivers/crypto/atmel-tdes.c b/drivers/crypto/atmel-tdes.c index 3b2a92029b16f9..d3bd8b72c2c95c 100644 --- a/drivers/crypto/atmel-tdes.c +++ b/drivers/crypto/atmel-tdes.c @@ -294,8 +294,8 @@ static int atmel_tdes_crypt_pdc_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, @@ -619,8 +619,8 @@ static int atmel_tdes_crypt_dma_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, -- cgit 1.3-korg
12a0adfe498ccrypto: atmel-tdes - fix DMA sync direction
1 file changed · +4 −5
drivers/crypto/atmel-tdes.c+4 −5 modifieddiff --git a/drivers/crypto/atmel-tdes.c b/drivers/crypto/atmel-tdes.c index d15b2e943447ef..813ed47e60cceb 100644 --- a/drivers/crypto/atmel-tdes.c +++ b/drivers/crypto/atmel-tdes.c @@ -294,8 +294,8 @@ static int atmel_tdes_crypt_pdc_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, @@ -619,8 +619,8 @@ static int atmel_tdes_crypt_dma_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, -- cgit 1.3-korg
5281e6e23023crypto: atmel-tdes - fix DMA sync direction
1 file changed · +4 −5
drivers/crypto/atmel-tdes.c+4 −5 modifieddiff --git a/drivers/crypto/atmel-tdes.c b/drivers/crypto/atmel-tdes.c index d234495f1115b8..6870a13342e22c 100644 --- a/drivers/crypto/atmel-tdes.c +++ b/drivers/crypto/atmel-tdes.c @@ -304,8 +304,8 @@ static int atmel_tdes_crypt_pdc_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, @@ -655,8 +655,8 @@ static int atmel_tdes_crypt_dma_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, -- cgit 1.3-korg
863d11b39277crypto: atmel-tdes - fix DMA sync direction
1 file changed · +4 −5
drivers/crypto/atmel-tdes.c+4 −5 modifieddiff --git a/drivers/crypto/atmel-tdes.c b/drivers/crypto/atmel-tdes.c index 3b2a92029b16f9..d3bd8b72c2c95c 100644 --- a/drivers/crypto/atmel-tdes.c +++ b/drivers/crypto/atmel-tdes.c @@ -294,8 +294,8 @@ static int atmel_tdes_crypt_pdc_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, @@ -619,8 +619,8 @@ static int atmel_tdes_crypt_dma_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, -- cgit 1.3-korg
b5f5df801d16crypto: atmel-tdes - fix DMA sync direction
1 file changed · +4 −5
drivers/crypto/atmel-tdes.c+4 −5 modifieddiff --git a/drivers/crypto/atmel-tdes.c b/drivers/crypto/atmel-tdes.c index 278c0df3c92f26..643e507f9c0209 100644 --- a/drivers/crypto/atmel-tdes.c +++ b/drivers/crypto/atmel-tdes.c @@ -294,8 +294,8 @@ static int atmel_tdes_crypt_pdc_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, @@ -619,8 +619,8 @@ static int atmel_tdes_crypt_dma_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, -- cgit 1.3-korg
c8a9a647532fcrypto: atmel-tdes - fix DMA sync direction
1 file changed · +4 −5
drivers/crypto/atmel-tdes.c+4 −5 modifieddiff --git a/drivers/crypto/atmel-tdes.c b/drivers/crypto/atmel-tdes.c index 278c0df3c92f26..643e507f9c0209 100644 --- a/drivers/crypto/atmel-tdes.c +++ b/drivers/crypto/atmel-tdes.c @@ -294,8 +294,8 @@ static int atmel_tdes_crypt_pdc_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, @@ -619,8 +619,8 @@ static int atmel_tdes_crypt_dma_stop(struct atmel_tdes_dev *dd) dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE); dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE); } else { - dma_sync_single_for_device(dd->dev, dd->dma_addr_out, - dd->dma_size, DMA_FROM_DEVICE); + dma_sync_single_for_cpu(dd->dev, dd->dma_addr_out, + dd->dma_size, DMA_FROM_DEVICE); /* copy data */ count = atmel_tdes_sg_copy(&dd->out_sg, &dd->out_offset, -- cgit 1.3-korg
Vulnerability mechanics
Root cause
"Incorrect DMA synchronization direction: the output buffer is synced with dma_sync_single_for_device() (CPU→device) instead of dma_sync_single_for_cpu() (device→CPU) before the CPU reads the data."
Attack vector
An attacker who can submit DES/TDES crypto operations to the atmel-tdes driver on a non-coherent platform may observe stale or corrupted output data. When the driver finishes a DMA transfer, it calls dma_sync_single_for_device() on the output buffer, which flushes CPU caches toward memory rather than invalidating caches before the CPU reads. This can cause the CPU to read stale cache lines instead of the freshly DMA-written data. The bug is triggered during normal cryptographic operation — no special payload is needed beyond any valid DES/TDES request that goes through the PDC or DMA completion paths in atmel_tdes_crypt_pdc_stop() and atmel_tdes_crypt_dma_stop() [patch_id=2659905].
Affected code
The bug is in drivers/crypto/atmel-tdes.c in two functions: atmel_tdes_crypt_pdc_stop() (around line 294) and atmel_tdes_crypt_dma_stop() (around line 619). Both functions call dma_sync_single_for_device() on dd->dma_addr_out with direction DMA_FROM_DEVICE when they should call dma_sync_single_for_cpu() [patch_id=2659905].
What the fix does
The patch changes two call sites in drivers/crypto/atmel-tdes.c: in atmel_tdes_crypt_pdc_stop() (line ~294) and atmel_tdes_crypt_dma_stop() (line ~619). Both previously called dma_sync_single_for_device() on dd->dma_addr_out with direction DMA_FROM_DEVICE, which is semantically wrong — that API prepares the CPU cache for device access, but the device has already written the data. The fix replaces it with dma_sync_single_for_cpu(), which invalidates CPU cache lines so the subsequent atmel_tdes_sg_copy() reads the actual DMA output from memory [patch_id=2659905].
Preconditions
- configThe system must run on a non-coherent platform (e.g., ARM) where CPU caches are not automatically coherent with DMA.
- configThe atmel-tdes driver must be in use and processing DES/TDES crypto requests.
- authNo authentication or special privileges beyond the ability to submit crypto operations are required.
Generated on May 27, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
5- git.kernel.org/stable/c/12a0adfe498cd5d87e6365d7ca5f6b3eed79e523nvd
- git.kernel.org/stable/c/5281e6e2302362f6b75b70cbfe4098d2a25dafd9nvd
- git.kernel.org/stable/c/863d11b3927703ad95077c81a8a6489c5c7872f7nvd
- git.kernel.org/stable/c/b5f5df801d161ba244f391519cbff2f4e5c6edc2nvd
- git.kernel.org/stable/c/c8a9a647532f5c2a04180352693215e24e9dba03nvd
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