CVE-2026-89772 - btrfs: write-protect folios during data writeback
Brief
CVE ID : CVE-2026-89772
Published : Sept. 11, 2026, 8:20 p. m.
- 32 minutes ago
Description : In the Linux kernel, the following vulnerability has been resolved:
btrfs: write-protect folios during data writeback
commit 095be159f3eb ("btrfs: unify folio dirty flag clearing") replaced the folio_clear_dirty_for_io() call in extent_write_cache_pages() with a plain folio_test_dirty() check. Besides clearing the dirty flag, folio_clear_dirty_for_io() also calls folio_mkclean(), which write-protects the shared mmap PTEs mapping the folio.
Note that we still do call folio_clear_dirty_for_io() later in submit_one_sector() when we clear dirty on the last sector of the folio (the only sector for non-subpage cases). But we lost this early call in extent_write_cache_pages().