{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-80685", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2026-80685" ], "published": "2026-08-28T06:53:24Z", "summary": "mm/util: don't read __page_2 for order-1 folios in snapshot_page()", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/util: don't read __page_2 for order-1 folios in snapshot_page()\n\nsnapshot_page() currently reads __page_2 after checking nr_pages > 1, but\nit should only do so when nr_pages > 2.\n\nIf an order-1 folio is allocated at the end of a vmemmap section,\n__page_2 will not exist and reading it will cause a fault.\n\nDuring DLPAR memory remove on a 22 TB ppc64le LPAR, snapshot_page() oopsed\non the page isolation path while reading an order-1 folio's __page_2 from\nan adjacent absent section (unmapped vmemmap).\n\nFix this to avoid reading memmap that doesn't exist (e.g., a vmemmap\nhole).", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:13", "name": "linux" }, "versions": [ "1:6.18.29-1+rpt1", "1:6.18.33-1+rpt1", "1:6.18.34-1+rpt1", "1:6.18.39-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.18.29+rpt-rpi-2712", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v6", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v7", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v8", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v8-rt", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-2712", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v6", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v7", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v8", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v8-rt", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-2712", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v6", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v7", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v8", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v8-rt", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-2712", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v6", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v7", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v8", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v8-rt", "binary_version": "1:6.18.39-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.18.29-1+rpt1": { "linux_commit": "66318c5b5cd8145a662303af12ed39ac07eb27cc", "upstream_version": "6.18.29", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.44" }, "1:6.18.33-1+rpt1": { "linux_commit": "95b85bebbedcaedfa7ca79116ed38b7376fba412", "upstream_version": "6.18.33", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.44" }, "1:6.18.34-1+rpt1": { "linux_commit": "c8c7494100e99ee05b11aaa4f0588a223a63d1af", "upstream_version": "6.18.34", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.44" }, "1:6.18.39-1+rpt1": { "linux_commit": "60ea684a8ace97bb0db1a16e20753bdd6ab371ff", "upstream_version": "6.18.39", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.44" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-80685" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/9668ffe0e2a5e2399dce281620198a2e415871fc" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/c649324571206a30949765320b91ccdb4c1722dc" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/7441d6348c70738e9ed307510db171c7a9b3f4bf" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-09-21T13:30:03Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.1, "cvss_v3_severity": "High", "scenario": "AV:L - Reachable via local read(2) on /proc/kpageflags or /proc/kpagecount (kpage_read\u2192stable_page_flags/get_kpage_count\u2192snapshot_page); the reported production crash also occurs on the memory-hotplug page-isolation dump_page path during offline_pages/DLPAR, with no network or physical-bus entry point.\nAC:L - A container/user-namespace root can sequentially scan PFNs via /proc/kpageflags until snapshot_page hits an order-1 folio at a vmemmap section boundary; on large SPARSEMEM_VMEMMAP systems such folios exist naturally (22 TB ppc64le LPAR oops) without races or attacker-uncontrollable timing.\nPR:L - /proc/kpage* is mode 0400 (root-only); exploitation needs only namespace/container root or CAP_SYS_ADMIN in a user namespace to read host proc on typical Docker/K8s/cloud nodes\u2014not init-namespace root; the DLPAR offline path needs admin but is not the lowest-privilege vector.\nUI:N - The attacker performs their own /proc/kpageflags reads or triggers kernel debug dumps; no separate victim action such as opening a file, mounting a filesystem, or approving a prompt is required beyond having local proc access.\nS:U - Impact is a kernel oops/panic within the host kernel security boundary; there is no VM escape, IOMMU bypass, or cross-authority resource access beyond crashing or destabilizing the shared kernel.\nC:H - snapshot_page() performs memcpy of a full struct page from foliop->__page_2 when only two pages are valid for order-1 folios, reading beyond allocated vmemmap into an unmapped hole; this out-of-bounds kernel read can expose adjacent mapped memmap bytes to the snapshot buffer on some layouts before faulting.\nI:N - The defect is a read past valid folio memmap that page-faults in kernel mode; memcpy only fills a local page_snapshot buffer and does not corrupt kernel objects, enable arbitrary writes, or provide a control-flow hijack primitive.\nA:H - Reading absent vmemmap for order-1 folios at section boundaries causes a supervisor page fault and kernel oops, as demonstrated during DLPAR memory remove on ppc64le; repeated /proc/kpageflags scanning can reliably panic or hang large-memory cloud/LPAR hosts." } } }