{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-99164", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.398Z", "datePublished": "2026-10-28T10:35:16.694Z", "dateUpdated": "2026-10-31T12:44:24.973Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-31T12:44:24.973Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nspi: imx: fix slab corruption from undersized DMA bounce buffers\n\nSince commit faa8e404ad8e (\"spi: imx: support dynamic burst length for\nECSPI DMA mode\"), the driver allocates its private DMA TX/RX buffers\nwith kzalloc(dma_len), where dma_len is only rounded up to 4 bytes, but\nmaps, syncs and unmaps them with DMA_CACHE_ALIGNED_LEN(dma_len), i.e.\nrounded up to the cache line size. As a result, the DMA API operates on\nmemory beyond the end of the allocation.\n\nThis was observed on a custom i.MX8MP platform with an mcp251xfd CAN\ncontroller under heavy RPMSG load, as a series of refcount_t warnings\ntriggered from rpmsg_recv_done() in virtio_rpmsg_bus:\n\n refcount_t: addition on 0; use-after-free.\n refcount_t: underflow; use-after-free.\n refcount_t: saturated; leaking memory.\n\nLeading finally to an \"Unable to handle kernel paging request\" oops.\nReproducing this problem took between 30 minutes and roughly 30 hours\nunder the same workload.\n\nHardware watchpoints on the refcount of a struct rpmsg_endpoint showed\nit was overwritten from 2 to 1 by __pi_memcpy_generic() in the\nirq/155-spi2.0 thread. Additionally it was found that a \"normal\"\nrpmsg_recv_done() took 11µs +/-2µs from its kref_get to kref_put. In\nthe error case the same sequence took about 215µs +/-10µs. Based on\nthis, an LLM was used to identify the size mismatch fixed here.\n\nAllocate the buffers with DMA_CACHE_ALIGNED_LEN(dma_len) so they cover\nthe full mapped length, and use the same length for\ndma_sync_single_for_cpu() to stay consistent with map and unmap.\n\nWith this patch applied, the same workload ran for more than 200 hours\nwithout the problem reproducing." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - A local caller can issue a 64-byte SPI_IOC_MESSAGE through spidev_ioctl()->spidev_message()->spi_sync()->spi_transfer_one_message()->spi_imx_transfer_one()->spi_imx_dma_transfer()->spi_imx_dma_tx_data_handle(). The faulty length is generated by spi_imx_dma_map(), not supplied by a remote CAN message.\nAC:L - spi_imx_can_dma() accepts caller-controlled transfers of at least 64 bytes; on arm64, 64 bytes deterministically makes spi_imx_dma_map() map 128 bytes after spi_imx_dma_tx_data_handle() allocated 64. The caller can repeat transfers and set word_delay to widen the corruption window without an uncontrollable hardware fault.\nPR:L - spidev_open() and spidev_ioctl() contain no capable() check, so an ordinary account with access to an existing /dev/spidev node can submit the transfer. Independently, can_create() and raw_sendmsg() let an unprivileged local user drive qualifying MCP251xFD CAN-FD SPI transfers on an already-up interface.\nUI:N - The attacker invokes spidev_ioctl() or CAN raw_sendmsg() directly, and those operations reach the faulty DMA mapping without another user mounting media, opening a file, or approving a transfer.\nS:U - spi_imx_dma_map() and spi_imx_dma_unmap() corrupt neighboring allocations in the same host kernel; the path crosses no VM, IOMMU, or other security-authority boundary.\nC:H - The oversized DMA_FROM_DEVICE cache maintenance reverted an adjacent struct rpmsg_endpoint refcount from 2 to 1, allowing __ept_release() to free an endpoint while it remained in use. This demonstrated UAF can expose reclaimed kernel-object contents.\nI:H - spi_imx_dma_unmap() invalidates cache lines beyond the undersized dma_rx_buf, demonstrably altering an adjacent rpmsg_endpoint refcount and creating a UAF. Reclaiming that freed object can convert the slab corruption into attacker-influenced writes or control-flow corruption.\nA:H - The corrupted rpmsg_endpoint refcount produced addition-on-zero, underflow, and saturation warnings and ultimately an Unable to handle kernel paging request oops, demonstrating a kernel crash." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/spi/spi-imx.c" ], "versions": [ { "version": "faa8e404ad8e686cb98c51dc507fdcacfb8020ce", "lessThan": "2777f6637da02da84c9c1ff92f413ce0f0995084", "status": "affected", "versionType": "git" }, { "version": "faa8e404ad8e686cb98c51dc507fdcacfb8020ce", "lessThan": "59eb22641f0c526dd064390b11cff99ae87c2858", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/spi/spi-imx.c" ], "versions": [ { "version": "7.0", "status": "affected" }, { "version": "0", "lessThan": "7.0", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.13", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.2.13" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/2777f6637da02da84c9c1ff92f413ce0f0995084" }, { "url": "https://git.kernel.org/stable/c/59eb22641f0c526dd064390b11cff99ae87c2858" } ], "title": "spi: imx: fix slab corruption from undersized DMA bounce buffers", "x_generator": { "engine": "bippy-1.2.0" } } } }