{"id":"CVE-2026-99164","state":"PUBLISHED","title":"spi: imx: fix slab corruption from undersized DMA bounce buffers","description":"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.","publishedAt":"2026-10-28T10:35:16.694Z","updatedAt":"2026-10-28T10:35:16.694Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"faa8e404ad8e686cb98c51dc507fdcacfb8020ce","status":"affected","lessThan":"2777f6637da02da84c9c1ff92f413ce0f0995084","versionType":"git"},{"version":"faa8e404ad8e686cb98c51dc507fdcacfb8020ce","status":"affected","lessThan":"59eb22641f0c526dd064390b11cff99ae87c2858","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/spi/spi-imx.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.0","versionType":"semver"},{"version":"7.2.13","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/spi/spi-imx.c"]}],"references":["https://git.kernel.org/stable/c/2777f6637da02da84c9c1ff92f413ce0f0995084","https://git.kernel.org/stable/c/59eb22641f0c526dd064390b11cff99ae87c2858"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/99xxx/CVE-2026-99164.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99164","state":"PUBLISHED","datePublished":"2026-10-28T10:35:16.694Z","dateUpdated":"2026-10-28T10:35:16.694Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.398Z"},"containers":{"cna":{"title":"spi: imx: fix slab corruption from undersized DMA bounce buffers","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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"faa8e404ad8e686cb98c51dc507fdcacfb8020ce","status":"affected","lessThan":"2777f6637da02da84c9c1ff92f413ce0f0995084","versionType":"git"},{"version":"faa8e404ad8e686cb98c51dc507fdcacfb8020ce","status":"affected","lessThan":"59eb22641f0c526dd064390b11cff99ae87c2858","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/spi/spi-imx.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.0","versionType":"semver"},{"version":"7.2.13","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/spi/spi-imx.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/2777f6637da02da84c9c1ff92f413ce0f0995084"},{"url":"https://git.kernel.org/stable/c/59eb22641f0c526dd064390b11cff99ae87c2858"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-28T10:35:16.694Z"},"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}