{"apiVersion":"1.0","identifier":"CVE-2026-72043","description":"In the Linux kernel, the following vulnerability has been resolved: LoongArch: Fix missing dirty page tracking in {pte,pmd}_wrprotect() When hardware page table walker (PTW) is enabled on LoongArch, the CPU may set _PAGE_DIRTY directly in the page table entry during a write TLB miss, without going through the software TLB store handler. The software TLB store handler (tlbex.S:254) sets both _PAGE_DIRTY and_PAGE_MODIFIED together: ori t0, t0, (_PAGE_VALID | _PAGE_DIRTY | _PAGE_MODIFIED) Since hardware PTW only sets _PAGE_DIRTY, the software-only bit, i.e. _PAGE_MODIFIED is left unchanged. This creates a window where a PTE has _PAGE_DIRTY set (hardware knows the page is dirty) but _PAGE_MODIFIED clear (software is unaware). When fork()/clone() triggers copy-on-write, __copy_present_ptes() calls pte_wrprotect(), which unconditionally clears both the _PAGE_WRITE and _PAGE_DIRTY bits: pte_val(pte) &= ~(_PAGE_WRITE | _PAGE_DIRTY); Since _PAGE_MODIFIED was never set, the dirtiness information is lost completely. Subsequently, when memory pressure triggers page reclaim, page_mkclean() / try_to_unmap() sees the page as clean (i.e. pte_dirty() returns false) and the page may be freed without writeback, causing data corruption. Fix this by propagating the _PAGE_DIRTY bit to the _PAGE_MODIFIED bit in both pte_wrprotect() and pmd_wrprotect() before clearing writeable bits: if (pte_val(pte) & _PAGE_DIRTY) pte_val(pte) |= _PAGE_MODIFIED; The pmd_wrprotect() fix handles the CONFIG_TRANSPARENT_HUGEPAGE case, where pmd entries need the same treatment. This ensures the software dirty tracking bit (checked by pte_dirty() and pmd_dirty(), which read both the _PAGE_DIRTY and _PAGE_MODIFIED bits) is preserved across fork COW write-protection. The issue was found by the LTP madvise09 test case, which exercises page reclaim after -madvise(MADV_FREE), write and fork- operation sequence on private anonymous mappings.","publishedAt":"2026-08-15T06:21:13","lastModifiedAt":"2026-08-17T06:18:02","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-72043","cvssScore":7.1,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","epssProbability":0.0016,"riskScore":0.72,"affectedProduct":"Linux kernel","affectedVersions":"unknown","vulnerabilityType":"Kernel","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-72043","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-72043","en":"https://www.redsauce.net/en/cves/CVE-2026-72043","fr":"https://www.redsauce.net/fr/cves/CVE-2026-72043","pt":"https://www.redsauce.net/pt/cves/CVE-2026-72043","de":"https://www.redsauce.net/de/cves/CVE-2026-72043","sk":"https://www.redsauce.net/sk/cves/CVE-2026-72043","el":"https://www.redsauce.net/el/cves/CVE-2026-72043"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-72043"}}