GHSA-M7QH-P3GF-GCV8
Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-08-13 15:34In the Linux kernel, the following vulnerability has been resolved:
iommufd: Set upper bounds on cache invalidation entry_num and entry_len
iommufd_hwpt_invalidate() takes a user-controlled entry_num and entry_len, each bounded only by U32_MAX. An entry_len beyond the kernel's struct size makes the copy helper verify the extra bytes are zero, scanning that excess in one uninterruptible pass; a multi-gigabyte value over zeroed user memory trips the soft-lockup watchdog.
A large entry_num is the other half, driving the backend invalidation loop with no reschedule. The VT-d nested handler, for one, copies each entry and flushes caches per iteration, pinning the CPU on a non-preemptible kernel.
Cap both in the ioctl. entry_len is held under PAGE_SIZE, above any request struct, and entry_num under 1 << 19, the order of a hardware invalidation queue and well beyond any real batch, bounding the per-call loop length.
{
"affected": [],
"aliases": [
"CVE-2026-64289"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-25T10:17:09Z",
"severity": "MODERATE"
},
"details": "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 U32_MAX. An entry_len beyond the kernel\u0027s 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 \u003c\u003c 19, the order of a hardware invalidation\nqueue and well beyond any real batch, bounding the per-call loop length.",
"id": "GHSA-m7qh-p3gf-gcv8",
"modified": "2026-08-13T15:34:19Z",
"published": "2026-07-25T12:31:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64289"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2c6381d90898089287e0a358f06f89f6b4b389f2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/32ca4aed2a66205b072fcfecabe220289a8149ff"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4d70986002f2f3eaaed89124fb2522bded38b016"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d2bd041e0efaf7d81789779b135279d18b33d6d5"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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