{"id":"CVE-2026-64496","state":"PUBLISHED","title":"iio: event: Fix event FIFO reset race","description":"In the Linux kernel, the following vulnerability has been resolved:\n\niio: event: Fix event FIFO reset race\n\n`iio_event_getfd()` creates the event file descriptor with\n`anon_inode_getfd()`, which allocates a new fd, creates the anonymous\nfile and installs it in the process fd table before returning to the\ncaller.\n\nThe IIO code resets the event FIFO after `anon_inode_getfd()` has returned,\nbut before `IIO_GET_EVENT_FD_IOCTL` has copied the fd number to userspace.\nBut since fd tables are shared between threads, another thread can guess\nthe newly allocated fd number and issue a `read()` on it as soon as the fd\nhas been installed.\n\nThis means the `kfifo_to_user()` in `iio_event_chrdev_read()` can run in\nparallel with the `kfifo_reset_out()` in `iio_event_getfd()`.\n\nThe kfifo documentation says that `kfifo_reset_out()` is only safe when it\nis called from the reader thread and there is only one concurrent reader.\nOtherwise it is dangerous and must be handled in the same way as\n`kfifo_reset()`.\n\nIf that happens, `kfifo_to_user()` can advance the FIFO `out` index based\non state from before the reset, after the reset has already moved the `out`\nindex to the current `in` index. That can leave the FIFO with an `out`\nindex past the `in` index. A later `read()` can then see an underflowed\nFIFO length and copy more data than the event FIFO buffer contains. This\ncan result in an out-of-bounds read and leak adjacent kernel memory to\nuserspace.\n\nMove the FIFO reset before `anon_inode_getfd()`. At that point the event fd is\nmarked busy, but the new fd has not been installed yet, so userspace cannot\naccess it while the FIFO is reset.","publishedAt":"2026-07-25T08:51:53.194Z","updatedAt":"2026-10-19T20:48:37.305Z","severity":{"score":7.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"9dc84ba4be5bbeb29ee49efe6cea2cb32c461424","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"d16a702ca7d29c0b7a9b509339d1b044a1cadb32","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"a13ef1adbc62085b21b546b07b0be7e2fbf52150","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"0d4a646d7f87ea3625fafe387043fddc6a2f5e7f","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"72c6aa8e0d74eab91b8694cde97dec088c248fee","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"9edefd4c56bee3fe331e0355d1f10a533134999d","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"f187dc5a4c4846ffa07d9bda6e760837ed005574","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"af791d295737ea6b6ff2c8d8488462a49c14af01","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iio/industrialio-event.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.15","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","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-event.c"]}],"references":["https://git.kernel.org/stable/c/9dc84ba4be5bbeb29ee49efe6cea2cb32c461424","https://git.kernel.org/stable/c/d16a702ca7d29c0b7a9b509339d1b044a1cadb32","https://git.kernel.org/stable/c/a13ef1adbc62085b21b546b07b0be7e2fbf52150","https://git.kernel.org/stable/c/0d4a646d7f87ea3625fafe387043fddc6a2f5e7f","https://git.kernel.org/stable/c/72c6aa8e0d74eab91b8694cde97dec088c248fee","https://git.kernel.org/stable/c/9edefd4c56bee3fe331e0355d1f10a533134999d","https://git.kernel.org/stable/c/f187dc5a4c4846ffa07d9bda6e760837ed005574","https://git.kernel.org/stable/c/af791d295737ea6b6ff2c8d8488462a49c14af01"],"weaknesses":["CWE-362"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64496.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64496","state":"PUBLISHED","datePublished":"2026-07-25T08:51:53.194Z","dateUpdated":"2026-10-19T20:48:37.305Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.792Z"},"containers":{"cna":{"title":"iio: event: Fix event FIFO reset race","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\niio: event: Fix event FIFO reset race\n\n`iio_event_getfd()` creates the event file descriptor with\n`anon_inode_getfd()`, which allocates a new fd, creates the anonymous\nfile and installs it in the process fd table before returning to the\ncaller.\n\nThe IIO code resets the event FIFO after `anon_inode_getfd()` has returned,\nbut before `IIO_GET_EVENT_FD_IOCTL` has copied the fd number to userspace.\nBut since fd tables are shared between threads, another thread can guess\nthe newly allocated fd number and issue a `read()` on it as soon as the fd\nhas been installed.\n\nThis means the `kfifo_to_user()` in `iio_event_chrdev_read()` can run in\nparallel with the `kfifo_reset_out()` in `iio_event_getfd()`.\n\nThe kfifo documentation says that `kfifo_reset_out()` is only safe when it\nis called from the reader thread and there is only one concurrent reader.\nOtherwise it is dangerous and must be handled in the same way as\n`kfifo_reset()`.\n\nIf that happens, `kfifo_to_user()` can advance the FIFO `out` index based\non state from before the reset, after the reset has already moved the `out`\nindex to the current `in` index. That can leave the FIFO with an `out`\nindex past the `in` index. A later `read()` can then see an underflowed\nFIFO length and copy more data than the event FIFO buffer contains. This\ncan result in an out-of-bounds read and leak adjacent kernel memory to\nuserspace.\n\nMove the FIFO reset before `anon_inode_getfd()`. At that point the event fd is\nmarked busy, but the new fd has not been installed yet, so userspace cannot\naccess it while the FIFO is reset."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"9dc84ba4be5bbeb29ee49efe6cea2cb32c461424","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"d16a702ca7d29c0b7a9b509339d1b044a1cadb32","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"a13ef1adbc62085b21b546b07b0be7e2fbf52150","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"0d4a646d7f87ea3625fafe387043fddc6a2f5e7f","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"72c6aa8e0d74eab91b8694cde97dec088c248fee","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"9edefd4c56bee3fe331e0355d1f10a533134999d","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"f187dc5a4c4846ffa07d9bda6e760837ed005574","versionType":"git"},{"version":"b91accafbb1031b80d22ad83576877ff2f8b4774","status":"affected","lessThan":"af791d295737ea6b6ff2c8d8488462a49c14af01","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iio/industrialio-event.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.15","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","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-event.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/9dc84ba4be5bbeb29ee49efe6cea2cb32c461424"},{"url":"https://git.kernel.org/stable/c/d16a702ca7d29c0b7a9b509339d1b044a1cadb32"},{"url":"https://git.kernel.org/stable/c/a13ef1adbc62085b21b546b07b0be7e2fbf52150"},{"url":"https://git.kernel.org/stable/c/0d4a646d7f87ea3625fafe387043fddc6a2f5e7f"},{"url":"https://git.kernel.org/stable/c/72c6aa8e0d74eab91b8694cde97dec088c248fee"},{"url":"https://git.kernel.org/stable/c/9edefd4c56bee3fe331e0355d1f10a533134999d"},{"url":"https://git.kernel.org/stable/c/f187dc5a4c4846ffa07d9bda6e760837ed005574"},{"url":"https://git.kernel.org/stable/c/af791d295737ea6b6ff2c8d8488462a49c14af01"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","baseScore":7.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - Exploitation uses local open(), ioctl(), and read() operations on /dev/iio:deviceX; no network-reachable path exists.\nAC:L - The attacker controls both racing threads and can predict the lowest available event fd, repeatedly race its installation, and stall the read using a userspace page fault.\nPR:L - The kernel path has no capability or authentication check; an ordinary user granted device-node access can invoke the vulnerable ioctl and read operations.\nUI:N - No victim action is required, and supported IIO drivers can generate events automatically through sensor interrupts.\nS:U - The vulnerability affects the kernel hosting the attacking process and does not inherently cross a VM, IOMMU, or separate security-authority boundary.\nC:H - The underflowed FIFO length permits an attacker-sized out-of-bounds read beyond the 256-byte event buffer, exposing adjacent kernel heap memory and potentially sensitive pointers or data.\nI:N - The path copies kernel data to userspace and corrupts only the FIFO read index; masked FIFO accesses provide no out-of-bounds write or control-flow modification primitive.\nA:H - An oversized read crossing the containing slab object triggers BUG() with hardened usercopy, causing a kernel oops or panic and allowing repeated denial of service."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:56:44.840Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"6.12.96"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-64496","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:41:26.474365Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-362","lang":"en","type":"CWE","description":"CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:48:37.305Z"}}]}}}