ghsa-mq33-37wv-8g5g
Vulnerability from github
Published
2025-09-05 18:31
Modified
2025-09-05 18:31
Details

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

habanalabs: fix UAF in export_dmabuf()

As soon as we'd inserted a file reference into descriptor table, another thread could close it. That's fine for the case when all we are doing is returning that descriptor to userland (it's a race, but it's a userland race and there's nothing the kernel can do about it). However, if we follow fd_install() with any kind of access to objects that would be destroyed on close (be it the struct file itself or anything destroyed by its ->release()), we have a UAF.

dma_buf_fd() is a combination of reserving a descriptor and fd_install(). habanalabs export_dmabuf() calls it and then proceeds to access the objects destroyed on close. In particular, it grabs an extra reference to another struct file that will be dropped as part of ->release() for ours; that "will be" is actually "might have already been".

Fix that by reserving descriptor before anything else and do fd_install() only when everything had been set up. As a side benefit, we no longer have the failure exit with file already created, but reference to underlying file (as well as ->dmabuf_export_cnt, etc.) not grabbed yet; unlike dma_buf_fd(), fd_install() can't fail.

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{
  "affected": [],
  "aliases": [
    "CVE-2025-38722"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-09-04T16:15:41Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nhabanalabs: fix UAF in export_dmabuf()\n\nAs soon as we\u0027d inserted a file reference into descriptor table, another\nthread could close it.  That\u0027s fine for the case when all we are doing is\nreturning that descriptor to userland (it\u0027s a race, but it\u0027s a userland\nrace and there\u0027s nothing the kernel can do about it).  However, if we\nfollow fd_install() with any kind of access to objects that would be\ndestroyed on close (be it the struct file itself or anything destroyed\nby its -\u003erelease()), we have a UAF.\n\ndma_buf_fd() is a combination of reserving a descriptor and fd_install().\nhabanalabs export_dmabuf() calls it and then proceeds to access the\nobjects destroyed on close.  In particular, it grabs an extra reference to\nanother struct file that will be dropped as part of -\u003erelease() for ours;\nthat \"will be\" is actually \"might have already been\".\n\nFix that by reserving descriptor before anything else and do fd_install()\nonly when everything had been set up.  As a side benefit, we no longer\nhave the failure exit with file already created, but reference to\nunderlying file (as well as -\u003edmabuf_export_cnt, etc.) not grabbed yet;\nunlike dma_buf_fd(), fd_install() can\u0027t fail.",
  "id": "GHSA-mq33-37wv-8g5g",
  "modified": "2025-09-05T18:31:17Z",
  "published": "2025-09-05T18:31:17Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38722"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/33927f3d0ecdcff06326d6e4edb6166aed42811c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/40deceb38f9db759772d1c289c28fd2a543f57fc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/55c232d7e0241f1d5120b595e7a9de24c75ed3d8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c07886761fd6251db6938d4e747002e3d150d231"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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