mm/huge_memory: update file PMD counter before folio_put()

Summary

In the Linux kernel, the following vulnerability has been resolved: mm/huge_memory: update file PMD counter before folio_put() __split_huge_pmd_locked() updates the file/shmem RSS counter after dropping the PMD mapping's folio reference. If folio_put() drops the last reference, mm_counter_file() can later read freed folio state via folio_test_swapbacked(). Move the counter update before folio_put().

Timeline

1. Jun 25, 2026, 8:39 AM UTCCVE published
2. Oct 16, 2026, 3:26 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 19, 2026, 7:57 PM UTCRecord last updated

Affected versions

• Linux Linux

  From fadae2953072e9005c5f1d64e1049edb043494dc · fixed in 84b3212b166b446faea27ebebb7161405ffceef9; From fadae2953072e9005c5f1d64e1049edb043494dc · fixed in 108963978a681c0c468d279cac2b930c27672877; From fadae2953072e9005c5f1d64e1049edb043494dc · fixed in 459771c9cf30f378bdbd30fc65d17f7eb931bb59; From fadae2953072e9005c5f1d64e1049edb043494dc · fixed in ae9d4caf6f133e884cf5fcda4982c493b35e5194; From fadae2953072e9005c5f1d64e1049edb043494dc · fixed in 6c29a8ba084e89499ca77b947e07ae817f9c16ce; From fadae2953072e9005c5f1d64e1049edb043494dc · fixed in 5f5b604e1e6bde4e889199168ee80fe8306d06ad; From fadae2953072e9005c5f1d64e1049edb043494dc · fixed in ed5b030931292c94133437ac5e5ff580e498eabd; From fadae2953072e9005c5f1d64e1049edb043494dc · fixed in 8d878059924f12c1bc24556a92ec56add74de3c8

• Linux Linux

  4.19

• KernelLinux

  From 4.19.0 · fixed in 5.10.259; From 5.11.0 · fixed in 5.15.210; From 5.16.0 · fixed in 6.1.176; From 6.2.0 · fixed in 6.6.143; From 6.7.0 · fixed in 6.12.94; From 6.13.0 · fixed in 6.18.36; From 6.19.0 · fixed in 7.0.13

References 8