{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80682","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-26T14:34:25.784Z","datePublished":"2026-08-28T06:52:49.498Z","dateUpdated":"2026-08-29T06:22:09.064Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-29T06:22:09.064Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nriscv/mm: use physical alignment for vmemmap_start_pfn\n\nRISC-V computes vmemmap_start_pfn by rounding phys_ram_base down to\nVMEMMAP_ADDR_ALIGN.  That alignment must therefore be expressed in the\nphysical-address domain.\n\nCommit 476849b0fba4 (\"riscv/mm: align vmemmap to maximal folio size\")\nattempted to account for the maximal folio alignment by feeding\nMAX_FOLIO_VMEMMAP_ALIGN directly into VMEMMAP_ADDR_ALIGN.  However,\nMAX_FOLIO_VMEMMAP_ALIGN is measured in bytes of struct page storage,\nwhereas VMEMMAP_ADDR_ALIGN is used to align a physical address.\n\nThe mask-based compound_info encoding requires pfn_to_page(0) to be\nnaturally aligned to MAX_FOLIO_VMEMMAP_ALIGN.  Commit 9f94db4c7eaa\n(\"mm/sparse: check memmap alignment for compound_info_has_mask()\") added a\ncheck for that requirement and exposed the unit mismatch on systems such\nas QEMU virt, where the DRAM base is not aligned to MAX_FOLIO_NR_PAGES *\nPAGE_SIZE.\n\nHere is the log:\n[    0.000000][    C0] ------------[ cut here ]------------\n[    0.000000][    C0] WARNING: mm/sparse.c:365 at sparse_init+0x58a/0x6fe, CPU#0: swapper/0\n[    0.000000][    C0] Modules linked in:\n[    0.000000][    C0] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 7.2.0-rc3-g1d8304bdd65f #2 PREEMPT \n[    0.000000][    C0] Hardware name: riscv-virtio,qemu (DT)\n[    0.000000][    C0] epc : sparse_init+0x58a/0x6fe\n[    0.000000][    C0]  ra : sparse_init+0x58a/0x6fe\n[    0.000000][    C0] epc : ffffffff86851c88 ra : ffffffff86851c88 sp : ffffffff88807a30\n[    0.000000][    C0]  gp : ffffffff8a3bf240 tp : ffffffff88842080 t0 : ff600000ffab6000\n[    0.000000][    C0]  t1 : 000000017fab6000 t2 : 65203a6573726363 s0 : ffffffff88807bc0\n[    0.000000][    C0]  s1 : 000000000e000000 a0 : 0000000000000007 a1 : 0000000000000000\n[    0.000000][    C0]  a2 : 0000000000000002 a3 : ffffffff86851c88 a4 : 0000000000000000\n[    0.000000][    C0]  a5 : ffffffff88843080 a6 : 0000000000000003 a7 : 0000000000000000\n[    0.000000][    C0]  s2 : ff60000000000000 s3 : 0040000000000000 s4 : 0004000000000000\n[    0.000000][    C0]  s5 : ffffffff8a4d92e0 s6 : ff600000ffab55e0 s7 : ffffffff88384d00\n[    0.000000][    C0]  s8 : 0000000000000003 s9 : ffffffff88384cc1 s10: ffffffff88384cc0\n[    0.000000][    C0]  s11: ffffffff8a4daae0 t3 : ffffffff915e8b20 t4 : ffffffff915e8b20\n[    0.000000][    C0]  t5 : ffffffff915e8b20 t6 : ffffffff915e8bc8 ssp : 0000000000000000\n[    0.000000][    C0] status: 0000000200000100 badaddr: ffffffff86851c88 cause: 0000000000000003\n[    0.000000][    C0] [<ffffffff86851c88>] sparse_init+0x58a/0x6fe\n[    0.000000][    C0] [<ffffffff8683d396>] mm_core_init_early+0x116/0x1e30\n[    0.000000][    C0] [<ffffffff86801edc>] start_kernel+0xd2/0x848\n\nConvert MAX_FOLIO_VMEMMAP_ALIGN to the equivalent physical alignment\nbefore using it in VMEMMAP_ADDR_ALIGN.  This keeps the existing\nround_down() logic while making the resulting vmemmap base satisfy the\nmask-alignment requirement."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The flaw is set during early boot in arch/riscv/mm/init.c setup_bootmem()/sparse_init(), and runtime impact is reached through local memory-management syscalls (mmap, page faults, compound folio allocation) invoking compound_head(); no network, adjacent-network, or remote protocol path exists.\nAC:L - On affected RISC-V 64 kernels with HUGETLB/HVO enabled (RISC-V defconfig) and DRAM bases such as QEMU virt where phys_ram_base is not aligned to MAX_FOLIO_NR_PAGES*PAGE_SIZE, the wrong vmemmap_start_pfn and misaligned pfn_to_page(0) occur deterministically every boot without races or attacker-uncontrollable layout.\nPR:L - The broken vmemmap alignment is established automatically at boot before any credentials exist; once running, an unprivileged local user can trigger compound folio allocation and freeing (anonymous mmap, THP, hugetlbfs) that exercise mask-based compound_head() with no capability or namespace gate.\nUI:N - No victim interaction is required beyond normal operation of an already-affected system; the attacker does not need another user to mount filesystems, open devices, or perform discretionary actions to reach the broken compound-page paths.\nS:U - Impact is kernel memory and page-metadata corruption within the host kernel security authority; it does not cross a VM, hypervisor, IOMMU/DMA, or sandbox boundary into a separate security domain.\nC:H - Misaligned pfn_to_page(0) breaks compound_info mask decoding so compound_head() can map tail struct pages to incorrect heads, enabling out-of-bounds reads of adjacent kernel page metadata and folio contents through routine MM operations (get_user_pages, compaction, isolation).\nI:H - Resolving the wrong compound head corrupts folio refcount, mapping, and LRU state and directs kernel read/write operations to unintended physical pages, providing a defensible arbitrary kernel-memory corruption primitive leveragable for privilege escalation.\nA:H - Incorrect compound_head() resolution can oops or panic the kernel during page isolation, compaction, THP, hugetlb, and I/O pin paths; sparse_init() VM_WARN_ON_ONCE on standard QEMU virt confirms the alignment violation is real on common RISC-V deployments."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/riscv/mm/init.c"],"versions":[{"version":"476849b0fba4450f5adf22196bcff9c24c673bc4","lessThan":"11ad86830a78ea4e1942afc73c10e4ca8e69e03f","status":"affected","versionType":"git"},{"version":"476849b0fba4450f5adf22196bcff9c24c673bc4","lessThan":"45ebe4540817cb540a59e4dc04014ac5dddc9990","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/riscv/mm/init.c"],"versions":[{"version":"7.1","status":"affected"},{"version":"0","lessThan":"7.1","status":"unaffected","versionType":"semver"},{"version":"7.1.8","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.1.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/11ad86830a78ea4e1942afc73c10e4ca8e69e03f"},{"url":"https://git.kernel.org/stable/c/45ebe4540817cb540a59e4dc04014ac5dddc9990"}],"title":"riscv/mm: use physical alignment for vmemmap_start_pfn","x_generator":{"engine":"bippy-1.2.0"}}}}