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CVE-2026-43486: Linux

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    Описание

    Оригинално описание

    In the Linux kernel, the following vulnerability has been resolved: arm64: contpte: fix set_access_flags() no-op check for SMMU/ATS faults contpte_ptep_set_access_flags() compared the gathered ptep_get() value against the requested entry to detect no-ops. ptep_get() ORs AF/dirty from all sub-PTEs in the CONT block, so a dirty sibling can make the target appear already-dirty. When the gathered value matches entry, the function returns 0 even though the target sub-PTE still has PTE_RDONLY set in hardware. For a CPU with FEAT_HAFDBS this gathered view is fine, since hardware may set AF/dirty on any sub-PTE and CPU TLB behavior is effectively gathered across the CONT range. But page-table walkers that evaluate each descriptor individually (e.g. a CPU without DBM support, or an SMMU without HTTU, or with HA/HD disabled in CD.TCR) can keep faulting on the unchanged target sub-PTE, causing an infinite fault loop. Gathering can therefore cause false no-ops when only a sibling has been updated: - write faults: target still has PTE_RDONLY (needs PTE_RDONLY cleared) - read faults: target still lacks PTE_AF Fix by checking each sub-PTE against the requested AF/dirty/write state (the same bits consumed by __ptep_set_access_flags()), using raw per-PTE values rather than the gathered ptep_get() view, before returning no-op. Keep using the raw target PTE for the write-bit unfold decision. Per Arm ARM (DDI 0487) D8.7.1 ("The Contiguous bit"), any sub-PTE in a CONT range may become the effective cached translation and software must maintain consistent attributes across the range.

    Засегнати продукти

    • Linux Linux: 4602e5757bcceb231c3a13c36c373ad4a750eddb преди 05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0; 4602e5757bcceb231c3a13c36c373ad4a750eddb преди 6f92a7a8b48a523f910ef25dd83808710724f59b; 4602e5757bcceb231c3a13c36c373ad4a750eddb преди 09d620555e59768776090073a2c59d2bc8506eb3; 4602e5757bcceb231c3a13c36c373ad4a750eddb преди 97c5550b763171dbef61e6239cab372b9f9cd4a2
    • Linux Linux: 6.9; преди 6.9; 6.12.78 до 6.12.*; 6.18.19 до 6.18.*; 6.19.9 до 6.19.*; от 7.0 нататък

    История

    • 13 май 2026 Публикувано

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    CVE-2026-43486: Linux | freedomonline.bg