{"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"}}}}