222 lines
13 KiB
JSON
222 lines
13 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-72043",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-08-09T03:40:39.902Z",
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"datePublished": "2026-08-15T05:52:02.505Z",
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"dateUpdated": "2026-08-17T05:39:42.678Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-08-17T05:39:42.678Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nLoongArch: Fix missing dirty page tracking in {pte,pmd}_wrprotect()\n\nWhen hardware page table walker (PTW) is enabled on LoongArch, the CPU\nmay set _PAGE_DIRTY directly in the page table entry during a write TLB\nmiss, without going through the software TLB store handler. The software\nTLB store handler (tlbex.S:254) sets both _PAGE_DIRTY and_PAGE_MODIFIED\ntogether:\n\n ori t0, t0, (_PAGE_VALID | _PAGE_DIRTY | _PAGE_MODIFIED)\n\nSince hardware PTW only sets _PAGE_DIRTY, the software-only bit, i.e.\n_PAGE_MODIFIED is left unchanged. This creates a window where a PTE has\n_PAGE_DIRTY set (hardware knows the page is dirty) but _PAGE_MODIFIED\nclear (software is unaware).\n\nWhen fork()/clone() triggers copy-on-write, __copy_present_ptes() calls\npte_wrprotect(), which unconditionally clears both the _PAGE_WRITE and\n_PAGE_DIRTY bits:\n\n pte_val(pte) &= ~(_PAGE_WRITE | _PAGE_DIRTY);\n\nSince _PAGE_MODIFIED was never set, the dirtiness information is lost\ncompletely. Subsequently, when memory pressure triggers page reclaim,\npage_mkclean() / try_to_unmap() sees the page as clean (i.e. pte_dirty()\nreturns false) and the page may be freed without writeback, causing data\ncorruption.\n\nFix this by propagating the _PAGE_DIRTY bit to the _PAGE_MODIFIED bit in\nboth pte_wrprotect() and pmd_wrprotect() before clearing writeable bits:\n\n if (pte_val(pte) & _PAGE_DIRTY)\n pte_val(pte) |= _PAGE_MODIFIED;\n\nThe pmd_wrprotect() fix handles the CONFIG_TRANSPARENT_HUGEPAGE case,\nwhere pmd entries need the same treatment.\n\nThis ensures the software dirty tracking bit (checked by pte_dirty() and\npmd_dirty(), which read both the _PAGE_DIRTY and _PAGE_MODIFIED bits) is\npreserved across fork COW write-protection.\n\nThe issue was found by the LTP madvise09 test case, which exercises page\nreclaim after \"madvise(MADV_FREE), write and fork\" operation sequence on\nprivate anonymous mappings."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
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"baseScore": 7.1,
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"baseSeverity": "HIGH"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:L - The bug is triggered via local syscalls (mmap/madvise/write/fork or clone) through dup_mmap()->copy_page_range()->pte_wrprotect() on LoongArch; it is not reachable from network-facing kernel services.\nAC:L - An unprivileged attacker can reliably reproduce the LTP madvise09 sequence (MADV_FREE, write, fork, then force reclaim) on LoongArch CPUs with hardware PTW; no races or victim-specific state beyond attacker-controlled memory pressure are required.\nPR:L - No special capabilities are needed; any local user can create private anonymous or file-backed COW mappings, write them, fork, and drive page reclaim using standard unprivileged syscalls.\nUI:N - Exploitation requires no action from another user; the attacker controls the full trigger sequence in their own process or in a service worker they operate.\nS:U - Impact is confined to kernel memory-management integrity on the host; it does not constitute a VM escape, sandbox escape, or IOMMU/DMA boundary bypass.\nC:H - Incorrectly treating hardware-dirty pages as clean during reclaim can free page frames without writeback or swap, leaving prior contents in the buddy allocator for reuse by other mappings and enabling cross-process information disclosure.\nI:H - Lost dirty tracking causes silent discard of modified pages during reclaim without writeback, corrupting private anonymous data and file-backed COW mappings when dirty pages are freed or swapped incorrectly.\nA:N - The defect causes silent data corruption rather than kernel oops, panic, or hang; the system remains operational even when pages are incorrectly reclaimed."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"arch/loongarch/include/asm/pgtable.h"
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],
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"versions": [
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{
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"version": "09cfefb7fa70c3af011b0db0a513fd80b2f18abc",
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"lessThan": "76f88650763a35cbf1384c65d66d096fa31cc58d",
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"status": "affected",
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"versionType": "git"
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"lessThan": "e8a916579e427af32f2de8213dfa23c5df6e6664",
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"status": "affected",
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"lessThan": "39bb21a4bff0d70058bf752d7b5aa2e2ccc864a9",
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"lessThan": "a65f49b6f7ece756394f8f0e85570020e7fd0e35",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "09cfefb7fa70c3af011b0db0a513fd80b2f18abc",
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"lessThan": "e483da960892c41fa7f0cf0d2fc2410d65a483d6",
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"status": "affected",
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"lessThan": "018e9828eb523c638fa3d9bdf0fd4956b74555b2",
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"status": "affected",
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}
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"arch/loongarch/include/asm/pgtable.h"
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],
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"versions": [
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{
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"version": "5.19",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "5.19",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.1.178",
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"lessThanOrEqual": "6.1.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.6.145",
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"lessThanOrEqual": "6.6.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.12.97",
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"lessThanOrEqual": "6.12.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18.40",
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"lessThanOrEqual": "6.18.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.1.5",
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"lessThanOrEqual": "7.1.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.2",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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"references": [
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"url": "https://git.kernel.org/stable/c/76f88650763a35cbf1384c65d66d096fa31cc58d"
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{
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"url": "https://git.kernel.org/stable/c/e8a916579e427af32f2de8213dfa23c5df6e6664"
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"url": "https://git.kernel.org/stable/c/39bb21a4bff0d70058bf752d7b5aa2e2ccc864a9"
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"url": "https://git.kernel.org/stable/c/a65f49b6f7ece756394f8f0e85570020e7fd0e35"
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"url": "https://git.kernel.org/stable/c/e483da960892c41fa7f0cf0d2fc2410d65a483d6"
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{
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"url": "https://git.kernel.org/stable/c/018e9828eb523c638fa3d9bdf0fd4956b74555b2"
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}
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],
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"title": "LoongArch: Fix missing dirty page tracking in {pte,pmd}_wrprotect()",
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