ghsa-ph55-5xqf-59r7
Vulnerability from github
Published
2024-03-11 18:31
Modified
2024-06-27 15:30
Details

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

drm: Don't unref the same fb many times by mistake due to deadlock handling

If we get a deadlock after the fb lookup in drm_mode_page_flip_ioctl() we proceed to unref the fb and then retry the whole thing from the top. But we forget to reset the fb pointer back to NULL, and so if we then get another error during the retry, before the fb lookup, we proceed the unref the same fb again without having gotten another reference. The end result is that the fb will (eventually) end up being freed while it's still in use.

Reset fb to NULL once we've unreffed it to avoid doing it again until we've done another fb lookup.

This turned out to be pretty easy to hit on a DG2 when doing async flips (and CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y). The first symptom I saw that drm_closefb() simply got stuck in a busy loop while walking the framebuffer list. Fortunately I was able to convince it to oops instead, and from there it was easier to track down the culprit.

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{
  "affected": [],
  "aliases": [
    "CVE-2023-52486"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-03-11T18:15:16Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm: Don\u0027t unref the same fb many times by mistake due to deadlock handling\n\nIf we get a deadlock after the fb lookup in drm_mode_page_flip_ioctl()\nwe proceed to unref the fb and then retry the whole thing from the top.\nBut we forget to reset the fb pointer back to NULL, and so if we then\nget another error during the retry, before the fb lookup, we proceed\nthe unref the same fb again without having gotten another reference.\nThe end result is that the fb will (eventually) end up being freed\nwhile it\u0027s still in use.\n\nReset fb to NULL once we\u0027ve unreffed it to avoid doing it again\nuntil we\u0027ve done another fb lookup.\n\nThis turned out to be pretty easy to hit on a DG2 when doing async\nflips (and CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y). The first symptom I\nsaw that drm_closefb() simply got stuck in a busy loop while walking\nthe framebuffer list. Fortunately I was able to convince it to oops\ninstead, and from there it was easier to track down the culprit.",
  "id": "GHSA-ph55-5xqf-59r7",
  "modified": "2024-06-27T15:30:38Z",
  "published": "2024-03-11T18:31:09Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-52486"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/376e21a9e4c2c63ee5d8d3aa74be5082c3882229"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/62f2e79cf9f4f47cc9dea9cebdf58d9f7b5695e0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9dd334a8245011ace45e53298175c7b659edb3e7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b4af63da9d94986c529d74499fdfe44289acd551"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bfd0feb1b109cb63b87fdcd00122603787c75a1a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cb4daf271302d71a6b9a7c01bd0b6d76febd8f0c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d7afdf360f4ac142832b098b4de974e867cc063c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f55261469be87c55df13db76dc945f6bcd825105"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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