Description
In the Linux kernel, the following vulnerability has been resolved:
spi: imx: fix slab corruption from undersized DMA bounce buffers
Since commit faa8e404ad8e ("spi: imx: support dynamic burst length for
ECSPI DMA mode"), the driver allocates its private DMA TX/RX buffers
with kzalloc(dma_len), where dma_len is only rounded up to 4 bytes, but
maps, syncs and unmaps them with DMA_CACHE_ALIGNED_LEN(dma_len), i.e.
rounded up to the cache line size. As a result, the DMA API operates on
memory beyond the end of the allocation.
This was observed on a custom i.MX8MP platform with an mcp251xfd CAN
controller under heavy RPMSG load, as a series of refcount_t warnings
triggered from rpmsg_recv_done() in virtio_rpmsg_bus:
refcount_t: addition on 0; use-after-free.
refcount_t: underflow; use-after-free.
refcount_t: saturated; leaking memory.
Leading finally to an "Unable to handle kernel paging request" oops.
Reproducing this problem took between 30 minutes and roughly 30 hours
under the same workload.
Hardware watchpoints on the refcount of a struct rpmsg_endpoint showed
it was overwritten from 2 to 1 by __pi_memcpy_generic() in the
irq/155-spi2.0 thread. Additionally it was found that a "normal"
rpmsg_recv_done() took 11µs +/-2µs from its kref_get to kref_put. In
the error case the same sequence took about 215µs +/-10µs. Based on
this, an LLM was used to identify the size mismatch fixed here.
Allocate the buffers with DMA_CACHE_ALIGNED_LEN(dma_len) so they cover
the full mapped length, and use the same length for
dma_sync_single_for_cpu() to stay consistent with map and unmap.
With this patch applied, the same workload ran for more than 200 hours
without the problem reproducing.
spi: imx: fix slab corruption from undersized DMA bounce buffers
Since commit faa8e404ad8e ("spi: imx: support dynamic burst length for
ECSPI DMA mode"), the driver allocates its private DMA TX/RX buffers
with kzalloc(dma_len), where dma_len is only rounded up to 4 bytes, but
maps, syncs and unmaps them with DMA_CACHE_ALIGNED_LEN(dma_len), i.e.
rounded up to the cache line size. As a result, the DMA API operates on
memory beyond the end of the allocation.
This was observed on a custom i.MX8MP platform with an mcp251xfd CAN
controller under heavy RPMSG load, as a series of refcount_t warnings
triggered from rpmsg_recv_done() in virtio_rpmsg_bus:
refcount_t: addition on 0; use-after-free.
refcount_t: underflow; use-after-free.
refcount_t: saturated; leaking memory.
Leading finally to an "Unable to handle kernel paging request" oops.
Reproducing this problem took between 30 minutes and roughly 30 hours
under the same workload.
Hardware watchpoints on the refcount of a struct rpmsg_endpoint showed
it was overwritten from 2 to 1 by __pi_memcpy_generic() in the
irq/155-spi2.0 thread. Additionally it was found that a "normal"
rpmsg_recv_done() took 11µs +/-2µs from its kref_get to kref_put. In
the error case the same sequence took about 215µs +/-10µs. Based on
this, an LLM was used to identify the size mismatch fixed here.
Allocate the buffers with DMA_CACHE_ALIGNED_LEN(dma_len) so they cover
the full mapped length, and use the same length for
dma_sync_single_for_cpu() to stay consistent with map and unmap.
With this patch applied, the same workload ran for more than 200 hours
without the problem reproducing.
Published:
2026-10-28
Score:
n/a
EPSS:
n/a
KEV:
No
Impact:
n/a
Action:
n/a
Analysis
Analysis and contextual insights are available on OpenCVE Cloud.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
|||||||||||||||
| Linux | Linux | affected |
|
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No data available yet.
Remediation
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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Advisories
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References
History
Wed, 28 Oct 2026 10:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: spi: imx: fix slab corruption from undersized DMA bounce buffers Since commit faa8e404ad8e ("spi: imx: support dynamic burst length for ECSPI DMA mode"), the driver allocates its private DMA TX/RX buffers with kzalloc(dma_len), where dma_len is only rounded up to 4 bytes, but maps, syncs and unmaps them with DMA_CACHE_ALIGNED_LEN(dma_len), i.e. rounded up to the cache line size. As a result, the DMA API operates on memory beyond the end of the allocation. This was observed on a custom i.MX8MP platform with an mcp251xfd CAN controller under heavy RPMSG load, as a series of refcount_t warnings triggered from rpmsg_recv_done() in virtio_rpmsg_bus: refcount_t: addition on 0; use-after-free. refcount_t: underflow; use-after-free. refcount_t: saturated; leaking memory. Leading finally to an "Unable to handle kernel paging request" oops. Reproducing this problem took between 30 minutes and roughly 30 hours under the same workload. Hardware watchpoints on the refcount of a struct rpmsg_endpoint showed it was overwritten from 2 to 1 by __pi_memcpy_generic() in the irq/155-spi2.0 thread. Additionally it was found that a "normal" rpmsg_recv_done() took 11µs +/-2µs from its kref_get to kref_put. In the error case the same sequence took about 215µs +/-10µs. Based on this, an LLM was used to identify the size mismatch fixed here. Allocate the buffers with DMA_CACHE_ALIGNED_LEN(dma_len) so they cover the full mapped length, and use the same length for dma_sync_single_for_cpu() to stay consistent with map and unmap. With this patch applied, the same workload ran for more than 200 hours without the problem reproducing. | |
| Title | spi: imx: fix slab corruption from undersized DMA bounce buffers | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-10-28T10:35:16.694Z
Reserved: 2026-09-25T10:25:14.398Z
Link: CVE-2026-99164
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.