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GHSA-Q844-WPFG-W2H9

Vulnerability from github – Published: 2024-09-13 09:30 – Updated: 2024-09-19 15:30
VLAI
Details

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

libfs: fix infinite directory reads for offset dir

After we switch tmpfs dir operations from simple_dir_operations to simple_offset_dir_operations, every rename happened will fill new dentry to dest dir's maple tree(&SHMEM_I(inode)->dir_offsets->mt) with a free key starting with octx->newx_offset, and then set newx_offset equals to free key + 1. This will lead to infinite readdir combine with rename happened at the same time, which fail generic/736 in xfstests(detail show as below).

  1. create 5000 files(1 2 3...) under one dir
  2. call readdir(man 3 readdir) once, and get one entry
  3. rename(entry, "TEMPFILE"), then rename("TEMPFILE", entry)
  4. loop 2~3, until readdir return nothing or we loop too many times(tmpfs break test with the second condition)

We choose the same logic what commit 9b378f6ad48cf ("btrfs: fix infinite directory reads") to fix it, record the last_index when we open dir, and do not emit the entry which index >= last_index. The file->private_data now used in offset dir can use directly to do this, and we also update the last_index when we llseek the dir file.

[brauner: only update last_index after seek when offset is zero like Jan suggested]

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2024-46701"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-09-13T07:15:05Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nlibfs: fix infinite directory reads for offset dir\n\nAfter we switch tmpfs dir operations from simple_dir_operations to\nsimple_offset_dir_operations, every rename happened will fill new dentry\nto dest dir\u0027s maple tree(\u0026SHMEM_I(inode)-\u003edir_offsets-\u003emt) with a free\nkey starting with octx-\u003enewx_offset, and then set newx_offset equals to\nfree key + 1. This will lead to infinite readdir combine with rename\nhappened at the same time, which fail generic/736 in xfstests(detail show\nas below).\n\n1. create 5000 files(1 2 3...) under one dir\n2. call readdir(man 3 readdir) once, and get one entry\n3. rename(entry, \"TEMPFILE\"), then rename(\"TEMPFILE\", entry)\n4. loop 2~3, until readdir return nothing or we loop too many\n   times(tmpfs break test with the second condition)\n\nWe choose the same logic what commit 9b378f6ad48cf (\"btrfs: fix infinite\ndirectory reads\") to fix it, record the last_index when we open dir, and\ndo not emit the entry which index \u003e= last_index. The file-\u003eprivate_data\nnow used in offset dir can use directly to do this, and we also update\nthe last_index when we llseek the dir file.\n\n[brauner: only update last_index after seek when offset is zero like Jan suggested]",
  "id": "GHSA-q844-wpfg-w2h9",
  "modified": "2024-09-19T15:30:49Z",
  "published": "2024-09-13T09:30:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-46701"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/308b4fc2403b335894592ee9dc212a5e58bb309f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/64a7ce76fb901bf9f9c36cf5d681328fc0fd4b5a"
    }
  ],
  "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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