{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2024-35798",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2024-35798"
  ],
  "published": "2024-05-17T13:23:58Z",
  "summary": "btrfs: fix race in read_extent_buffer_pages()",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix race in read_extent_buffer_pages()\n\nThere are reports from tree-checker that detects corrupted nodes,\nwithout any obvious pattern so possibly an overwrite in memory.\nAfter some debugging it turns out there's a race when reading an extent\nbuffer the uptodate status can be missed.\n\nTo prevent concurrent reads for the same extent buffer,\nread_extent_buffer_pages() performs these checks:\n\n    /* (1) */\n    if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))\n        return 0;\n\n    /* (2) */\n    if (test_and_set_bit(EXTENT_BUFFER_READING, &eb->bflags))\n        goto done;\n\nAt this point, it seems safe to start the actual read operation. Once\nthat completes, end_bbio_meta_read() does\n\n    /* (3) */\n    set_extent_buffer_uptodate(eb);\n\n    /* (4) */\n    clear_bit(EXTENT_BUFFER_READING, &eb->bflags);\n\nNormally, this is enough to ensure only one read happens, and all other\ncallers wait for it to finish before returning.  Unfortunately, there is\na racey interleaving:\n\n    Thread A | Thread B | Thread C\n    ---------+----------+---------\n       (1)   |          |\n             |    (1)   |\n       (2)   |          |\n       (3)   |          |\n       (4)   |          |\n             |    (2)   |\n             |          |    (1)\n\nWhen this happens, thread B kicks of an unnecessary read. Worse, thread\nC will see UPTODATE set and return immediately, while the read from\nthread B is still in progress.  This race could result in tree-checker\nerrors like this as the extent buffer is concurrently modified:\n\n    BTRFS critical (device dm-0): corrupted node, root=256\n    block=8550954455682405139 owner mismatch, have 11858205567642294356\n    expect [256, 18446744073709551360]\n\nFix it by testing UPTODATE again after setting the READING bit, and if\nit's been set, skip the unnecessary read.\n\n[ minor update of changelog ]",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.6.20-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-2712",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v6",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v7",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v7l",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v8",
            "binary_version": "1:6.6.20-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.6.20-1+rpt1": {
            "linux_commit": "6f16847710cc0502450788b9f12f0a14d3429668",
            "upstream_version": "6.6.20",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.24"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2024-35798"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0427c8ef8bbb7f304de42ef51d69c960e165e052"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3a25878a3378adce5d846300c9570f15aa7f7a80"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/2885d54af2c2e1d910e20d5c8045bae40e02fbc1"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ef1e68236b9153c27cb7cf29ead0c532870d4215"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T11:52:36Z"
  }
}