ghsa-9wr4-x5hv-2rw2
Vulnerability from github
Published
2024-03-15 21:30
Modified
2024-11-05 18:31
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Details

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

ocfs2: fix data corruption by fallocate

When fallocate punches holes out of inode size, if original isize is in the middle of last cluster, then the part from isize to the end of the cluster will be zeroed with buffer write, at that time isize is not yet updated to match the new size, if writeback is kicked in, it will invoke ocfs2_writepage()->block_write_full_page() where the pages out of inode size will be dropped. That will cause file corruption. Fix this by zero out eof blocks when extending the inode size.

Running the following command with qemu-image 4.2.1 can get a corrupted coverted image file easily.

qemu-img convert -p -t none -T none -f qcow2 $qcow_image \
         -O qcow2 -o compat=1.1 $qcow_image.conv

The usage of fallocate in qemu is like this, it first punches holes out of inode size, then extend the inode size.

fallocate(11, FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE, 2276196352, 65536) = 0
fallocate(11, 0, 2276196352, 65536) = 0

v1: https://www.spinics.net/lists/linux-fsdevel/msg193999.html v2: https://lore.kernel.org/linux-fsdevel/20210525093034.GB4112@quack2.suse.cz/T/

Show details on source website

To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2021-47114"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-03-15T21:15:06Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: fix data corruption by fallocate\n\nWhen fallocate punches holes out of inode size, if original isize is in\nthe middle of last cluster, then the part from isize to the end of the\ncluster will be zeroed with buffer write, at that time isize is not yet\nupdated to match the new size, if writeback is kicked in, it will invoke\nocfs2_writepage()-\u003eblock_write_full_page() where the pages out of inode\nsize will be dropped.  That will cause file corruption.  Fix this by\nzero out eof blocks when extending the inode size.\n\nRunning the following command with qemu-image 4.2.1 can get a corrupted\ncoverted image file easily.\n\n    qemu-img convert -p -t none -T none -f qcow2 $qcow_image \\\n             -O qcow2 -o compat=1.1 $qcow_image.conv\n\nThe usage of fallocate in qemu is like this, it first punches holes out\nof inode size, then extend the inode size.\n\n    fallocate(11, FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE, 2276196352, 65536) = 0\n    fallocate(11, 0, 2276196352, 65536) = 0\n\nv1: https://www.spinics.net/lists/linux-fsdevel/msg193999.html\nv2: https://lore.kernel.org/linux-fsdevel/20210525093034.GB4112@quack2.suse.cz/T/",
  "id": "GHSA-9wr4-x5hv-2rw2",
  "modified": "2024-11-05T18:31:58Z",
  "published": "2024-03-15T21:30:43Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-47114"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0a31dd6fd2f4e7db538fb6eb1f06973d81f8dd3b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/33e03adafb29eedae1bae9cdb50c1385279fcf65"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/624fa7baa3788dc9e57840ba5b94bc22b03cda57"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6bba4471f0cc1296fe3c2089b9e52442d3074b2e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a1700479524bb9cb5e8ae720236a6fabd003acae"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c8d5faee46242c3f33b8a71a4d7d52214785bfcc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cc2edb99ea606a45182b5ea38cc8f4e583aa0774"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cec4e857ffaa8c447f51cd8ab4e72350077b6770"
    }
  ],
  "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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