{"id":"CVE-2026-64289","title":"iommufd: Set upper bounds on cache invalidation entry_num and entry_len","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\niommufd: Set upper bounds on cache invalidation entry_num and entry_len\n\niommufd_hwpt_invalidate() takes a user-controlled entry_num and entry_len,\neach bounded only by…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 8c6eabae3807e048b9f17733af5e20500fbf858c < d2bd041e0efaf7d81789779b135279d18b33d6d5","Linux >= 8c6eabae3807e048b9f17733af5e20500fbf858c < 32ca4aed2a66205b072fcfecabe220289a8149ff","Linux >= 8c6eabae3807e048b9f17733af5e20500fbf858c < 2c6381d90898089287e0a358f06f89f6b4b389f2","Linux >= 8c6eabae3807e048b9f17733af5e20500fbf858c < 4d70986002f2f3eaaed89124fb2522bded38b016","Linux 6.8"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-06T16:33:46.830505Z"},"published":"2026-07-25","updated":"2026-11-06","sourceUpdated":"2026-11-06T16:34:32.610Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64289","references":[{"url":"https://git.kernel.org/stable/c/d2bd041e0efaf7d81789779b135279d18b33d6d5"},{"url":"https://git.kernel.org/stable/c/32ca4aed2a66205b072fcfecabe220289a8149ff"},{"url":"https://git.kernel.org/stable/c/2c6381d90898089287e0a358f06f89f6b4b389f2"},{"url":"https://git.kernel.org/stable/c/4d70986002f2f3eaaed89124fb2522bded38b016"}],"tags":["cve.org"],"epss":0.00159,"epssPercentile":0.05107,"ingestedAt":"2026-11-06T16:57:43.210Z","slug":"CVE-2026-64289","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\niommufd: Set upper bounds on cache invalidation entry_num and entry_len\n\niommufd_hwpt_invalidate() takes a user-controlled entry_num and entry_len,\neach bounded only by U32_MAX. An entry_len beyond the kernel's struct size\nmakes the copy helper verify the extra bytes are zero, scanning that excess\nin one uninterruptible pass; a multi-gigabyte value over zeroed user memory\ntrips the soft-lockup watchdog.\n\nA large entry_num is the other half, driving the backend invalidation loop\nwith no reschedule. The VT-d nested handler, for one, copies each entry and\nflushes caches per iteration, pinning the CPU on a non-preemptible kernel.\n\nCap both in the ioctl. entry_len is held under PAGE_SIZE, above any request\nstruct, and entry_num under 1 << 19, the order of a hardware invalidation\nqueue and well beyond any real batch, bounding the per-call loop length.\n\n## Affected\n\n- `Linux >= 8c6eabae3807e048b9f17733af5e20500fbf858c < d2bd041e0efaf7d81789779b135279d18b33d6d5`\n- `Linux >= 8c6eabae3807e048b9f17733af5e20500fbf858c < 32ca4aed2a66205b072fcfecabe220289a8149ff`\n- `Linux >= 8c6eabae3807e048b9f17733af5e20500fbf858c < 2c6381d90898089287e0a358f06f89f6b4b389f2`\n- `Linux >= 8c6eabae3807e048b9f17733af5e20500fbf858c < 4d70986002f2f3eaaed89124fb2522bded38b016`\n- `Linux 6.8`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}