riscv/mm: use physical alignment for vmemmap_start_pfn

Description

In the Linux kernel, the following vulnerability has been resolved: riscv/mm: use physical alignment for vmemmap_start_pfn RISC-V computes vmemmap_start_pfn by rounding phys_ram_base down to VMEMMAP_ADDR_ALIGN. That alignment must therefore be expressed in the physical-address domain. Commit 476849b0fba4 ("riscv/mm: align vmemmap to maximal folio size") attempted to account for the maximal folio alignment by feeding MAX_FOLIO_VMEMMAP_ALIGN directly into VMEMMAP_ADDR_ALIGN. However, MAX_FOLIO_VMEMMAP_ALIGN is measured in bytes of struct page storage, whereas VMEMMAP_ADDR_ALIGN is used to align a physical address. The mask-based compound_info encoding requires pfn_to_page(0) to be naturally aligned to MAX_FOLIO_VMEMMAP_ALIGN. Commit 9f94db4c7eaa ("mm/sparse: check memmap alignment for compound_info_has_mask()") added a check for that requirement and exposed the unit mismatch on systems such as QEMU virt, where the DRAM base is not aligned to MAX_FOLIO_NR_PAGES * PAGE_SIZE. Here is the log: [ 0.000000][ C0] ------------[ cut here ]------------ [ 0.000000][ C0] WARNING: mm/sparse.c:365 at sparse_init+0x58a/0x6fe, CPU#0: swapper/0 [ 0.000000][ C0] Modules linked in: [ 0.000000][ C0] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 7.2.0-rc3-g1d8304bdd65f #2 PREEMPT [ 0.000000][ C0] Hardware name: riscv-virtio,qemu (DT) [ 0.000000][ C0] epc : sparse_init+0x58a/0x6fe [ 0.000000][ C0] ra : sparse_init+0x58a/0x6fe [ 0.000000][ C0] epc : ffffffff86851c88 ra : ffffffff86851c88 sp : ffffffff88807a30 [ 0.000000][ C0] gp : ffffffff8a3bf240 tp : ffffffff88842080 t0 : ff600000ffab6000 [ 0.000000][ C0] t1 : 000000017fab6000 t2 : 65203a6573726363 s0 : ffffffff88807bc0 [ 0.000000][ C0] s1 : 000000000e000000 a0 : 0000000000000007 a1 : 0000000000000000 [ 0.000000][ C0] a2 : 0000000000000002 a3 : ffffffff86851c88 a4 : 0000000000000000 [ 0.000000][ C0] a5 : ffffffff88843080 a6 : 0000000000000003 a7 : 0000000000000000 [ 0.000000][ C0] s2 : ff60000000000000 s3 : 0040000000000000 s4 : 0004000000000000 [ 0.000000][ C0] s5 : ffffffff8a4d92e0 s6 : ff600000ffab55e0 s7 : ffffffff88384d00 [ 0.000000][ C0] s8 : 0000000000000003 s9 : ffffffff88384cc1 s10: ffffffff88384cc0 [ 0.000000][ C0] s11: ffffffff8a4daae0 t3 : ffffffff915e8b20 t4 : ffffffff915e8b20 [ 0.000000][ C0] t5 : ffffffff915e8b20 t6 : ffffffff915e8bc8 ssp : 0000000000000000 [ 0.000000][ C0] status: 0000000200000100 badaddr: ffffffff86851c88 cause: 0000000000000003 [ 0.000000][ C0] [<ffffffff86851c88>] sparse_init+0x58a/0x6fe [ 0.000000][ C0] [<ffffffff8683d396>] mm_core_init_early+0x116/0x1e30 [ 0.000000][ C0] [<ffffffff86801edc>] start_kernel+0xd2/0x848 Convert MAX_FOLIO_VMEMMAP_ALIGN to the equivalent physical alignment before using it in VMEMMAP_ADDR_ALIGN. This keeps the existing round_down() logic while making the resulting vmemmap base satisfy the mask-alignment requirement.

Timeline

Scores

EPSS (exploitation in 30 days)

0.18% · top 92% of all CVEs (12 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.

Affected products

• Linux · Linux

  • affected 476849b0fba4450f5adf22196bcff9c24c673bc4 – < 11ad86830a78ea4e1942afc73c10e4ca8e69e03f
  • affected 476849b0fba4450f5adf22196bcff9c24c673bc4 – < 45ebe4540817cb540a59e4dc04014ac5dddc9990

• Linux · Linux

  • affected 7.1
  • unaffected < 7.1
  • unaffected 7.1.8 – ≤ 7.1.*
  • unaffected 7.2 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-67558 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-80682](https://cveledger.app/badge/CVE-2026-80682.svg)](https://cveledger.app/cve/CVE-2026-80682)

Record last updated 29 Aug 2026, 06:22 UTC.