cve-2026-64567

{
  "cvss": 7.8,
  "datePublished": "2026-08-05T08:16:36.277",
  "dateUpdated": "2026-11-03T18:15:39.353",
  "description": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: reject free space cache with more entries than pages\n\nWhen loading a v1 free space cache, __load_free_space_cache() takes\nnum_entries and num_bitmaps straight from the on-disk\nbtrfs_free_space_header. That header is stored in the tree_root under a key\nwith type 0, which the tree-checker has no case for, so neither count is\nvalidated before the load trusts it.\n\nThe load loops num_entries times and maps the next page whenever the current\none runs out, going through io_ctl_check_crc() -> io_ctl_map_page(), which\ndoes io_ctl->pages[io_ctl->index++]. But pages[] is allocated in\nio_ctl_init() from the cache inode's i_size, not from num_entries:\n\n\tnum_pages = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);\n\tio_ctl->pages = kcalloc(num_pages, sizeof(struct page *), GFP_NOFS);\n\nSo if num_entries claims more records than the pages can hold, io_ctl->index\nruns off the end of pages[]. The write side never hits this because\nio_ctl_add_entry() and io_ctl_add_bitmap() both stop once\nio_ctl->index >= io_ctl->num_pages; the read side just never had the same\ncheck.\n\nTo trigger it, take a clean cache (num_entries = <N> here), set num_entries\nin the header to 0x10000, and fix up the leaf checksum so it still passes\nthe tree-checker. The cache inode has i_size = 65536, so num_pages is 16 and\npages[] is a 16-pointer (kmalloc-128) array. The load now tries to read\n65536 entries, io_ctl->index walks up to 16, and pages[16] is read past the\narray:\n\n  BUG: KASAN: slab-out-of-bounds in io_ctl_check_crc (fs/btrfs/free-space-cache.c:420 fs/btrfs/free-space-cache.c:565)\n  Read of size 8 at addr ffff88800c833a80 by task kworker/u8:3/58\n   io_ctl_check_crc (fs/btrfs/free-space-cache.c:420 fs/btrfs/free-space-cache.c:565)\n   __load_free_space_cache (fs/btrfs/free-space-cache.c:655 fs/btrfs/free-space-cache.c:820)\n   load_free_space_cache (fs/btrfs/free-space-cache.c:1017)\n   caching_thread (fs/btrfs/block-group.c:880)\n   btrfs_work_helper (fs/btrfs/async-thread.c:312)\n   process_one_work\n   worker_thread\n   kthread\n   ret_from_fork\n\nfree-space-cache.c:420 is io_ctl_map_page(), inlined into io_ctl_check_crc()\nat line 565, which is why that is the frame KASAN names. The out-of-bounds\nslot is then treated as a struct page and handed to crc32c(), so the bad\nread turns into a GP fault.\n\nAdd the missing check to io_ctl_check_crc(), which is where both the entry\nloop and the bitmap loop end up. When num_entries is too large the load now\nfails like any corrupt cache: __load_free_space_cache() drops it and rebuilds\nthe free space from the extent tree, so a valid cache is never rejected.",
  "id": "CVE-2026-64567",
  "raw": {
    "affected": [
      {
        "affectedData": [
          {
            "defaultStatus": "unaffected",
            "product": "Linux",
            "programFiles": [
              "fs/btrfs/free-space-cache.c"
            ],
            "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
            "vendor": "Linux",
            "versions": [
              {
                "lessThan": "8ded74c654a982dc8581a17b0caa7fcedb20de69",
                "status": "affected",
                "version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
                "versionType": "git"
              },
              {
                "lessThan": "c9c38066b6446e83668c041702bb639b0ca49363",
                "status": "affected",
                "version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
                "versionType": "git"
              },
              {
                "lessThan": "094734c7aaa2b36751dc32480a680a4952685e78",
                "status": "affected",
                "version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
                "versionType": "git"
              },
              {
                "lessThan": "33878ba25e2638bc0c61623d7a05c9ca2b74c039",
                "status": "affected",
                "version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
                "versionType": "git"
              },
              {
                "lessThan": "404a0b986e0b6e79738fdf1f0ebbbc43b9acd2a2",
                "status": "affected",
                "version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
                "versionType": "git"
              },
              {
                "lessThan": "5e1b2ca6b34939e70fb0785e8222b53cf060016f",
                "status": "affected",
                "version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
                "versionType": "git"
              },
              {
                "lessThan": "f9fef131fa3f59b857217f522fa5ea430d1b707c",
                "status": "affected",
                "version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
                "versionType": "git"
              },
              {
                "lessThan": "a2d8d5647ed854e38f941741aea45b9eb15a6350",
                "status": "affected",
                "version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
                "versionType": "git"
              }
            ]
          },
          {
            "defaultStatus": "affected",
            "product": "Linux",
            "programFiles": [
              "fs/btrfs/free-space-cache.c"
            ],
            "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
            "vendor": "Linux",
            "versions": [
              {
                "status": "affected",
                "version": "3.2"
              },
              {
                "lessThan": "3.2",
                "status": "unaffected",
                "version": "0",
                "versionType": "semver"
              },
              {
                "lessThanOrEqual": "5.10.*",
                "status": "unaffected",
                "version": "5.10.265",
                "versionType": "semver"
              },
              {
                "lessThanOrEqual": "5.15.*",
                "status": "unaffected",
                "version": "5.15.216",
                "versionType": "semver"
              },
              {
                "lessThanOrEqual": "6.1.*",
                "status": "unaffected",
                "version": "6.1.183",
                "versionType": "semver"
              },
              {
                "lessThanOrEqual": "6.6.*",
                "status": "unaffected",
                "version": "6.6.148",
                "versionType": "semver"
              },
              {
                "lessThanOrEqual": "6.12.*",
                "status": "unaffected",
                "version": "6.12.101",
                "versionType": "semver"
              },
              {
                "lessThanOrEqual": "6.18.*",
                "status": "unaffected",
                "version": "6.18.42",
                "versionType": "semver"
              },
              {
                "lessThanOrEqual": "7.1.*",
                "status": "unaffected",
                "version": "7.1.6",
                "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: reject free space cache with more entries than pages\n\nWhen loading a v1 free space cache, __load_free_space_cache() takes\nnum_entries and num_bitmaps straight from the on-disk\nbtrfs_free_space_header. That header is stored in the tree_root under a key\nwith type 0, which the tree-checker has no case for, so neither count is\nvalidated before the load trusts it.\n\nThe load loops num_entries times and maps the next page whenever the current\none runs out, going through io_ctl_check_crc() -> io_ctl_map_page(), which\ndoes io_ctl->pages[io_ctl->index++]. But pages[] is allocated in\nio_ctl_init() from the cache inode's i_size, not from num_entries:\n\n\tnum_pages = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);\n\tio_ctl->pages = kcalloc(num_pages, sizeof(struct page *), GFP_NOFS);\n\nSo if num_entries claims more records than the pages can hold, io_ctl->index\nruns off the end of pages[]. The write side never hits this because\nio_ctl_add_entry() and io_ctl_add_bitmap() both stop once\nio_ctl->index >= io_ctl->num_pages; the read side just never had the same\ncheck.\n\nTo trigger it, take a clean cache (num_entries = <N> here), set num_entries\nin the header to 0x10000, and fix up the leaf checksum so it still passes\nthe tree-checker. The cache inode has i_size = 65536, so num_pages is 16 and\npages[] is a 16-pointer (kmalloc-128) array. The load now tries to read\n65536 entries, io_ctl->index walks up to 16, and pages[16] is read past the\narray:\n\n  BUG: KASAN: slab-out-of-bounds in io_ctl_check_crc (fs/btrfs/free-space-cache.c:420 fs/btrfs/free-space-cache.c:565)\n  Read of size 8 at addr ffff88800c833a80 by task kworker/u8:3/58\n   io_ctl_check_crc (fs/btrfs/free-space-cache.c:420 fs/btrfs/free-space-cache.c:565)\n   __load_free_space_cache (fs/btrfs/free-space-cache.c:655 fs/btrfs/free-space-cache.c:820)\n   load_free_space_cache (fs/btrfs/free-space-cache.c:1017)\n   caching_thread (fs/btrfs/block-group.c:880)\n   btrfs_work_helper (fs/btrfs/async-thread.c:312)\n   process_one_work\n   worker_thread\n   kthread\n   ret_from_fork\n\nfree-space-cache.c:420 is io_ctl_map_page(), inlined into io_ctl_check_crc()\nat line 565, which is why that is the frame KASAN names. The out-of-bounds\nslot is then treated as a struct page and handed to crc32c(), so the bad\nread turns into a GP fault.\n\nAdd the missing check to io_ctl_check_crc(), which is where both the entry\nloop and the bitmap loop end up. When num_entries is too large the load now\nfails like any corrupt cache: __load_free_space_cache() drops it and rebuilds\nthe free space from the extent tree, so a valid cache is never rejected."
      }
    ],
    "id": "CVE-2026-64567",
    "lastModified": "2026-11-03T18:15:39.353",
    "metrics": {
      "cvssMetricV31": [
        {
          "cvssData": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "exploitabilityScore": 1.8,
          "impactScore": 5.9,
          "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
          "type": "Secondary"
        }
      ],
      "ssvcV203": [
        {
          "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "ssvcData": {
            "id": "CVE-2026-64567",
            "options": [
              {
                "exploitation": "none"
              },
              {
                "automatable": "no"
              },
              {
                "technicalImpact": "total"
              }
            ],
            "role": "CISA Coordinator",
            "timestamp": "2026-10-16T15:42:59.944567Z",
            "version": "2.0.3"
          }
        }
      ]
    },
    "published": "2026-08-05T08:16:36.277",
    "references": [
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "url": "https://git.kernel.org/stable/c/094734c7aaa2b36751dc32480a680a4952685e78"
      },
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "url": "https://git.kernel.org/stable/c/33878ba25e2638bc0c61623d7a05c9ca2b74c039"
      },
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "url": "https://git.kernel.org/stable/c/404a0b986e0b6e79738fdf1f0ebbbc43b9acd2a2"
      },
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "url": "https://git.kernel.org/stable/c/5e1b2ca6b34939e70fb0785e8222b53cf060016f"
      },
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "url": "https://git.kernel.org/stable/c/8ded74c654a982dc8581a17b0caa7fcedb20de69"
      },
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "url": "https://git.kernel.org/stable/c/a2d8d5647ed854e38f941741aea45b9eb15a6350"
      },
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "url": "https://git.kernel.org/stable/c/c9c38066b6446e83668c041702bb639b0ca49363"
      },
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "url": "https://git.kernel.org/stable/c/f9fef131fa3f59b857217f522fa5ea430d1b707c"
      }
    ],
    "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "vulnStatus": "Awaiting Analysis",
    "weaknesses": [
      {
        "description": [
          {
            "lang": "en",
            "value": "CWE-125"
          }
        ],
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ]
  },
  "severity": "HIGH",
  "source": "nvd",
  "title": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: reject free space cache with more entries..."
}