GHSA-GVJR-WRWM-XP44

Vulnerability from github – Published: 2025-12-30 15:30 – Updated: 2025-12-30 15:30
VLAI?
Details

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

m68k: Only force 030 bus error if PC not in exception table

__get_kernel_nofault() does copy data in supervisor mode when forcing a task backtrace log through /proc/sysrq_trigger. This is expected cause a bus error exception on e.g. NULL pointer dereferencing when logging a kernel task has no workqueue associated. This bus error ought to be ignored.

Our 030 bus error handler is ill equipped to deal with this:

Whenever ssw indicates a kernel mode access on a data fault, we don't even attempt to handle the fault and instead always send a SEGV signal (or panic). As a result, the check for exception handling at the fault PC (buried in send_sig_fault() which gets called from do_page_fault() eventually) is never used.

In contrast, both 040 and 060 access error handlers do not care whether a fault happened on supervisor mode access, and will call do_page_fault() on those, ultimately honoring the exception table.

Add a check in bus_error030 to call do_page_fault() in case we do have an entry for the fault PC in our exception table.

I had attempted a fix for this earlier in 2019 that did rely on testing pagefault_disabled() (see link below) to achieve the same thing, but this patch should be more generic.

Tested on 030 Atari Falcon.

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{
  "affected": [],
  "aliases": [
    "CVE-2023-54232"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-12-30T13:16:11Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nm68k: Only force 030 bus error if PC not in exception table\n\n__get_kernel_nofault() does copy data in supervisor mode when\nforcing a task backtrace log through /proc/sysrq_trigger.\nThis is expected cause a bus error exception on e.g. NULL\npointer dereferencing when logging a kernel task has no\nworkqueue associated. This bus error ought to be ignored.\n\nOur 030 bus error handler is ill equipped to deal with this:\n\nWhenever ssw indicates a kernel mode access on a data fault,\nwe don\u0027t even attempt to handle the fault and instead always\nsend a SEGV signal (or panic). As a result, the check\nfor exception handling at the fault PC (buried in\nsend_sig_fault() which gets called from do_page_fault()\neventually) is never used.\n\nIn contrast, both 040 and 060 access error handlers do not\ncare whether a fault happened on supervisor mode access,\nand will call do_page_fault() on those, ultimately honoring\nthe exception table.\n\nAdd a check in bus_error030 to call do_page_fault() in case\nwe do have an entry for the fault PC in our exception table.\n\nI had attempted a fix for this earlier in 2019 that did rely\non testing pagefault_disabled() (see link below) to achieve\nthe same thing, but this patch should be more generic.\n\nTested on 030 Atari Falcon.",
  "id": "GHSA-gvjr-wrwm-xp44",
  "modified": "2025-12-30T15:30:32Z",
  "published": "2025-12-30T15:30:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-54232"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1a6059f5ed57f48edfe7159404ff7d538d9d405b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2100e374251a8fc00cce1916cfc50f3cb652cbe3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/54fa25ffab2b700df5abd58c136d64a912c53953"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8bf8d5dade4c5e1d8a2386f29253ed28b5d87735"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/df1da53a7e98f0b2a0eb2241c154f148f2f2c1d8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e36a82bebbf7da814530d5a179bef9df5934b717"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ec15405b80fc15ffc87a23d01378ae061c1aba07"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f55cb52ec98b22125f5bda36391edb8894f7e8cf"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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