CVE-2026-80734: Software Security Vulnerability Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-rfxq-m8fc-mrw6",
  "modified" : "2026-10-11T15:30:56Z",
  "published" : "2026-09-03T15:32:14Z",
  "aliases" : [ "CVE-2026-80734" ],
  "details" : "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: initialize inode mapping flags for cached inodes\n\n[BUG]\nWhen running generic/795 with 8K block size, 4K page size, the test\nalways fails, triggering some ASSERT()s related to folio size:\n\n  795 (241074): drop_caches: 3\n  assertion failed: IS_ALIGNED(start, blocksize) && IS_ALIGNED(end + 1, blocksize), in extent_io.c:1404 (blocksize=8192 root=262 ino=258 start=16826368 end=16830463 mapping min order=0)\n  ------------[ cut here ]------------\n  kernel BUG at extent_io.c:1404!\n  Oops: invalid opcode: 0000 [#1] SMP\n  CPU: 8 UID: 0 PID: 241105 Comm: fsstress Tainted: G           OE       7.2.0-rc5-custom+ #442 PREEMPT(full)  f4bfb352566f3949f29c233ce6f735050a03b245\n  Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022\n  RIP: 0010:assert_folio_range.cold+0x3d/0x3f [btrfs]\n  Call Trace:\n   <TASK>\n   btrfs_read_folio+0x9e/0x170 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3]\n   prepare_one_folio.constprop.0+0x104/0x2a0 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3]\n   btrfs_buffered_write+0x285/0xa50 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3]\n   btrfs_do_write_iter+0x1aa/0x210 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3]\n   iter_file_splice_write+0x31a/0x540\n   direct_splice_actor+0x53/0x170\n   splice_direct_to_actor+0xe9/0x240\n   do_splice_direct+0x76/0xb0\n   vfs_copy_file_range+0x1fd/0x630\n   __x64_sys_copy_file_range+0xf9/0x220\n   do_syscall_64+0xe1/0x790\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\n   </TASK>\n  ---[ end trace 0000000000000000 ]---\n\nThe ASSERT() itself is added by a later patch.\nThe crash is triggered with that new debug patch, and without this fix.\n\n[CAUSE]\nIn the above case, the start 16826368 is properly 8K aligned, but the\nend (16830463 + 1) is not 8K aligned.\nFurthermore the mapping's minimal folio order is 0, not the expected 1\nfor 8K block size with 4K page size.\n\nSo this means some inodes do not have btrfs_set_inode_mapping_order()\ncalled on it.\n\nThe missing btrfs_set_inode_mapping_order() call happens for cached\ninodes, through the following events:\n\n- btrfs_create_new_inode() called for inode X\n  Which properly sets minimal folio order for the VFS inode.\n\n- btrfs_update_inode() called for inode X\n  Which calls btrfs_delayed_update_inode() to create a delayed_node\n  into root->delayed_nodes xarray.\n\n- Drop cache/memory pressure, evicting in-memory inode X\n  Which evicted the inode X, but delayed_node is still in\n  root->delayed_nodes for future reuse.\n\n- btrfs_iget() for inode X called again\n\n  btrfs_iget()\n  |- btrfs_iget_locked()\n  |  |- iget5_locked_rcu()\n  |     Which creates a new vfs_inode for btrfs, whose mapping still\n  |     has the minimal order as 0.\n  |\n  |- btrfs_read_locked_inode()\n     |- btrfs_fill_inode()\n     |  |- btrfs_get_delayed_node()\n     |     Which found out the previous node, and use that delayed\n     |     node to initialize the new inode.\n     |\n     |- filled = true;\n     |- if (filled) goto cache_index;\n        Which skips the btrfs_update_inode_mapping_flags() and\n\tbtrfs_set_inode_mapping_order() calls.\n\tSo the inode still has minimal folio order set as 0, not\n\tthe required 1.\n\nThus later page cache read will get a folio whose size is smaller than\nblock size, as the mapping has its minimal folio order set as 0 not 1,\nthen trigger the ASSERT().\n\n[FIX]\nMove the btrfs_update_inode_mapping_flags() and\nbtrfs_set_inode_mapping_order() calls under cache_index label,\nso that the mapping flags and minimal folio order is always set\nno matter if we have a cached inode.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-80734"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/0d26249671171ab759cb4fdce673554a690fa655"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/0ef349734a93227b45f65fc50a3311d1cc5f03e9"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/e18b8236c57fcc67d793bfc866f4bb2581be9f72"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-03T13:06:12Z"
  }
}