GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

FKIE_CVE-2026-80734

Vulnerability from fkie_nvd - Published: 2026-09-03 13:06 - Updated: 2026-09-04 05:17
Severity
8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: btrfs: initialize inode mapping flags for cached inodes [BUG] When running generic/795 with 8K block size, 4K page size, the test always fails, triggering some ASSERT()s related to folio size: 795 (241074): drop_caches: 3 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) ------------[ cut here ]------------ kernel BUG at extent_io.c:1404! Oops: invalid opcode: 0000 [#1] SMP CPU: 8 UID: 0 PID: 241105 Comm: fsstress Tainted: G OE 7.2.0-rc5-custom+ #442 PREEMPT(full) f4bfb352566f3949f29c233ce6f735050a03b245 Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:assert_folio_range.cold+0x3d/0x3f [btrfs] Call Trace: <TASK> btrfs_read_folio+0x9e/0x170 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3] prepare_one_folio.constprop.0+0x104/0x2a0 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3] btrfs_buffered_write+0x285/0xa50 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3] btrfs_do_write_iter+0x1aa/0x210 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3] iter_file_splice_write+0x31a/0x540 direct_splice_actor+0x53/0x170 splice_direct_to_actor+0xe9/0x240 do_splice_direct+0x76/0xb0 vfs_copy_file_range+0x1fd/0x630 __x64_sys_copy_file_range+0xf9/0x220 do_syscall_64+0xe1/0x790 entry_SYSCALL_64_after_hwframe+0x4b/0x53 </TASK> ---[ end trace 0000000000000000 ]--- The ASSERT() itself is added by a later patch. The crash is triggered with that new debug patch, and without this fix. [CAUSE] In the above case, the start 16826368 is properly 8K aligned, but the end (16830463 + 1) is not 8K aligned. Furthermore the mapping's minimal folio order is 0, not the expected 1 for 8K block size with 4K page size. So this means some inodes do not have btrfs_set_inode_mapping_order() called on it. The missing btrfs_set_inode_mapping_order() call happens for cached inodes, through the following events: - btrfs_create_new_inode() called for inode X Which properly sets minimal folio order for the VFS inode. - btrfs_update_inode() called for inode X Which calls btrfs_delayed_update_inode() to create a delayed_node into root->delayed_nodes xarray. - Drop cache/memory pressure, evicting in-memory inode X Which evicted the inode X, but delayed_node is still in root->delayed_nodes for future reuse. - btrfs_iget() for inode X called again btrfs_iget() |- btrfs_iget_locked() | |- iget5_locked_rcu() | Which creates a new vfs_inode for btrfs, whose mapping still | has the minimal order as 0. | |- btrfs_read_locked_inode() |- btrfs_fill_inode() | |- btrfs_get_delayed_node() | Which found out the previous node, and use that delayed | node to initialize the new inode. | |- filled = true; |- if (filled) goto cache_index; Which skips the btrfs_update_inode_mapping_flags() and btrfs_set_inode_mapping_order() calls. So the inode still has minimal folio order set as 0, not the required 1. Thus later page cache read will get a folio whose size is smaller than block size, as the mapping has its minimal folio order set as 0 not 1, then trigger the ASSERT(). [FIX] Move the btrfs_update_inode_mapping_flags() and btrfs_set_inode_mapping_order() calls under cache_index label, so that the mapping flags and minimal folio order is always set no matter if we have a cached inode.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0d26249671171ab759cb4fdce673554a690fa655
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0ef349734a93227b45f65fc50a3311d1cc5f03e9
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0d26249671171ab759cb4fdce673554a690fa655",
              "status": "affected",
              "version": "ecde48a1a6b3256bd49db8780bf37556b157783c",
              "versionType": "git"
            },
            {
              "lessThan": "0ef349734a93227b45f65fc50a3311d1cc5f03e9",
              "status": "affected",
              "version": "ecde48a1a6b3256bd49db8780bf37556b157783c",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ae584726e6eddf6cfbe49b3f4a78b3197716b6f8",
              "versionType": "git"
            },
            {
              "lessThan": "6.15",
              "status": "affected",
              "version": "6.14.6",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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) \u0026\u0026 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   \u003cTASK\u003e\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   \u003c/TASK\u003e\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\u0027s 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-\u003edelayed_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-\u003edelayed_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."
    }
  ],
  "id": "CVE-2026-80734",
  "lastModified": "2026-09-04T05:17:13.900",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-03T13:06:12.200",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0d26249671171ab759cb4fdce673554a690fa655"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0ef349734a93227b45f65fc50a3311d1cc5f03e9"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.