{"id":"CVE-2026-89940","state":"PUBLISHED","title":"iio: buffer: Tie IIO dma fence lock lifetime to the fence","description":"In the Linux kernel, the following vulnerability has been resolved:\n\niio: buffer: Tie IIO dma fence lock lifetime to the fence\n\nThe `iio_dma_fence` implementation currently uses a lock embedded in the\n`iio_dmabuf_priv`. But the `iio_dma_fence` can outlive the\n`iio_dmabuf_priv`, which can cause a use-after-free.\n\nTie the lifetime of the lock to the lifetime of the fence by embedding them\nin the same struct.\n\nWe can't just hold a reference to the `iio_dmabuf_priv` from the\n`iio_dma_fence` since `iio_buffer_dmabuf_release()` might sleep and the\nfence release callback is not allowed to sleep.\n\nNote that the `dma_fence` framework now has an internal lock that gets used\nwhen the passing `NULL` for `lock` in `dma_fence_init()`, but in order to\nallow this patch to be backportable use an external lock.","publishedAt":"2026-09-16T10:32:28.395Z","updatedAt":"2026-10-19T08:55:14.651Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f","status":"affected","lessThan":"6865d79fca17a80fbd60c12550ca9a5e0e20e0eb","versionType":"git"},{"version":"3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f","status":"affected","lessThan":"510497e31be4f241103507315a859e2085ccb081","versionType":"git"},{"version":"3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f","status":"affected","lessThan":"8b3e221590181a8beb3735bbabf166df02c839b5","versionType":"git"},{"version":"3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f","status":"affected","lessThan":"f25ec4627d935dedfb5fe83bd2c2678cdcc19611","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iio/industrialio-buffer.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.11","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.5","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/iio/industrialio-buffer.c"]}],"references":["https://git.kernel.org/stable/c/6865d79fca17a80fbd60c12550ca9a5e0e20e0eb","https://git.kernel.org/stable/c/510497e31be4f241103507315a859e2085ccb081","https://git.kernel.org/stable/c/8b3e221590181a8beb3735bbabf166df02c839b5","https://git.kernel.org/stable/c/f25ec4627d935dedfb5fe83bd2c2678cdcc19611"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89940.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89940","state":"PUBLISHED","datePublished":"2026-09-16T10:32:28.395Z","dateUpdated":"2026-10-19T08:55:14.651Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.776Z"},"containers":{"cna":{"title":"iio: buffer: Tie IIO dma fence lock lifetime to the fence","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\niio: buffer: Tie IIO dma fence lock lifetime to the fence\n\nThe `iio_dma_fence` implementation currently uses a lock embedded in the\n`iio_dmabuf_priv`. But the `iio_dma_fence` can outlive the\n`iio_dmabuf_priv`, which can cause a use-after-free.\n\nTie the lifetime of the lock to the lifetime of the fence by embedding them\nin the same struct.\n\nWe can't just hold a reference to the `iio_dmabuf_priv` from the\n`iio_dma_fence` since `iio_buffer_dmabuf_release()` might sleep and the\nfence release callback is not allowed to sleep.\n\nNote that the `dma_fence` framework now has an internal lock that gets used\nwhen the passing `NULL` for `lock` in `dma_fence_init()`, but in order to\nallow this patch to be backportable use an external lock."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f","status":"affected","lessThan":"6865d79fca17a80fbd60c12550ca9a5e0e20e0eb","versionType":"git"},{"version":"3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f","status":"affected","lessThan":"510497e31be4f241103507315a859e2085ccb081","versionType":"git"},{"version":"3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f","status":"affected","lessThan":"8b3e221590181a8beb3735bbabf166df02c839b5","versionType":"git"},{"version":"3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f","status":"affected","lessThan":"f25ec4627d935dedfb5fe83bd2c2678cdcc19611","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iio/industrialio-buffer.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.11","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.5","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/iio/industrialio-buffer.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/6865d79fca17a80fbd60c12550ca9a5e0e20e0eb"},{"url":"https://git.kernel.org/stable/c/510497e31be4f241103507315a859e2085ccb081"},{"url":"https://git.kernel.org/stable/c/8b3e221590181a8beb3735bbabf166df02c839b5"},{"url":"https://git.kernel.org/stable/c/f25ec4627d935dedfb5fe83bd2c2678cdcc19611"}],"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 - The use-after-free is reached through local IIO_BUFFER_DMABUF_ATTACH/ENQUEUE/DETACH ioctls on an anonymous iio:buffer fd from IIO_BUFFER_GET_FD_IOCTL on /dev/iio:deviceN; it is not reachable from network packet processing or adjacent-link protocols.\nAC:L - The attacker fully controls the lifetime mismatch: they attach and enqueue a DMA-BUF so the dma_fence lock lives in iio_dmabuf_priv, then detach so priv is freed while the fence remains in the DMA-BUF reservation, and later DMA_BUF_IOCTL_SYNC/wait takes that freed lock.\nPR:L - The IIO open and ioctl path has no capability check, only filesystem access to the device node. On Android phones, industrial converters, and embedded systems exposing this DMA-BUF buffer API, /dev/iio:device* is commonly group-accessible without init-namespace root.\nUI:N - The attacker opens the IIO device, issues the DMA-BUF attach/enqueue/detach ioctls, and waits on their own DMA-BUF file descriptor; no separate victim action is required.\nS:U - This is a standard in-kernel heap use-after-free of iio_dmabuf_priv within the host kernel's security authority, not a VM escape, IOMMU boundary bypass, or sandbox escape.\nC:H - The dma_fence retains a pointer to a spinlock embedded in freed iio_dmabuf_priv; later fence wait/sync operations use that lock, a slab use-after-free that can be turned into an arbitrary kernel memory read via heap spraying.\nI:H - The same use-after-free of iio_dmabuf_priv lets an attacker reclaim the object and corrupt dma_fence lock and callback state during later wait or signaling paths, enabling heap corruption, arbitrary write, and control-flow hijacking.\nA:H - Taking a spinlock in already-freed iio_dmabuf_priv memory causes a kernel oops, BUG, or panic; any use-after-free is high availability impact even when not fully exploited."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:55:14.651Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.18.51"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.2.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}