GHSA-PVGC-VPGW-88MQ

Vulnerability from github – Published: 2024-10-21 18:30 – Updated: 2025-11-04 00:31
VLAI?
Details

In the Linux kernel, the following vulnerability has been resolved:

ext4: update orig_path in ext4_find_extent()

In ext4_find_extent(), if the path is not big enough, we free it and set orig_path to NULL. But after reallocating and successfully initializing the path, we don't update orig_path, in which case the caller gets a valid path but a NULL ppath, and this may cause a NULL pointer dereference or a path memory leak. For example:

ext4_split_extent path = ppath = 2000 ext4_find_extent if (depth > path[0].p_maxdepth) kfree(path = 2000); orig_path = path = NULL; path = kcalloc() = 3000 ext4_split_extent_at(ppath = NULL) path = ppath; ex = path[depth].p_ext; // NULL pointer dereference!

================================================================== BUG: kernel NULL pointer dereference, address: 0000000000000010 CPU: 6 UID: 0 PID: 576 Comm: fsstress Not tainted 6.11.0-rc2-dirty #847 RIP: 0010:ext4_split_extent_at+0x6d/0x560 Call Trace: ext4_split_extent.isra.0+0xcb/0x1b0 ext4_ext_convert_to_initialized+0x168/0x6c0 ext4_ext_handle_unwritten_extents+0x325/0x4d0 ext4_ext_map_blocks+0x520/0xdb0 ext4_map_blocks+0x2b0/0x690 ext4_iomap_begin+0x20e/0x2c0 [...] ==================================================================

Therefore, orig_path is updated when the extent lookup succeeds, so that the caller can safely use path or ppath.

Severity ?
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2024-49881"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-10-21T18:15:10Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: update orig_path in ext4_find_extent()\n\nIn ext4_find_extent(), if the path is not big enough, we free it and set\n*orig_path to NULL. But after reallocating and successfully initializing\nthe path, we don\u0027t update *orig_path, in which case the caller gets a\nvalid path but a NULL ppath, and this may cause a NULL pointer dereference\nor a path memory leak. For example:\n\next4_split_extent\n  path = *ppath = 2000\n  ext4_find_extent\n    if (depth \u003e path[0].p_maxdepth)\n      kfree(path = 2000);\n      *orig_path = path = NULL;\n      path = kcalloc() = 3000\n  ext4_split_extent_at(*ppath = NULL)\n    path = *ppath;\n    ex = path[depth].p_ext;\n    // NULL pointer dereference!\n\n==================================================================\nBUG: kernel NULL pointer dereference, address: 0000000000000010\nCPU: 6 UID: 0 PID: 576 Comm: fsstress Not tainted 6.11.0-rc2-dirty #847\nRIP: 0010:ext4_split_extent_at+0x6d/0x560\nCall Trace:\n \u003cTASK\u003e\n ext4_split_extent.isra.0+0xcb/0x1b0\n ext4_ext_convert_to_initialized+0x168/0x6c0\n ext4_ext_handle_unwritten_extents+0x325/0x4d0\n ext4_ext_map_blocks+0x520/0xdb0\n ext4_map_blocks+0x2b0/0x690\n ext4_iomap_begin+0x20e/0x2c0\n[...]\n==================================================================\n\nTherefore, *orig_path is updated when the extent lookup succeeds, so that\nthe caller can safely use path or *ppath.",
  "id": "GHSA-pvgc-vpgw-88mq",
  "modified": "2025-11-04T00:31:40Z",
  "published": "2024-10-21T18:30:56Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-49881"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/11b230100d6801c014fab2afabc8bdea304c1b96"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5b4b2dcace35f618fe361a87bae6f0d13af31bc1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6766937d0327000ac1b87c97bbecdd28b0dd6599"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6801ed1298204d16a38571091e31178bfdc3c679"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a9fcb1717d75061d3653ed69365c8d45331815cd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b63481b3a388ee2df9e295f97273226140422a42"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ec0c0beb9b777cdd1edd7df9b36e0f3e67e2bdff"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f55ecc58d07a6c1f6d6d5b5af125c25f8da0bda2"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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