GHSA-FQ97-HV4F-CRM6

Vulnerability from github – Published: 2024-02-26 18:30 – Updated: 2024-04-17 18:31
VLAI
Details

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

x86/fpu: Stop relying on userspace for info to fault in xsave buffer

Before this change, the expected size of the user space buffer was taken from fx_sw->xstate_size. fx_sw->xstate_size can be changed from user-space, so it is possible construct a sigreturn frame where:

  • fx_sw->xstate_size is smaller than the size required by valid bits in fx_sw->xfeatures.
  • user-space unmaps parts of the sigrame fpu buffer so that not all of the buffer required by xrstor is accessible.

In this case, xrstor tries to restore and accesses the unmapped area which results in a fault. But fault_in_readable succeeds because buf + fx_sw->xstate_size is within the still mapped area, so it goes back and tries xrstor again. It will spin in this loop forever.

Instead, fault in the maximum size which can be touched by XRSTOR (taken from fpstate->user_size).

[ dhansen: tweak subject / changelog ]

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2024-26603"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-02-26T16:28:00Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/fpu: Stop relying on userspace for info to fault in xsave buffer\n\nBefore this change, the expected size of the user space buffer was\ntaken from fx_sw-\u003exstate_size. fx_sw-\u003exstate_size can be changed\nfrom user-space, so it is possible construct a sigreturn frame where:\n\n * fx_sw-\u003exstate_size is smaller than the size required by valid bits in\n   fx_sw-\u003exfeatures.\n * user-space unmaps parts of the sigrame fpu buffer so that not all of\n   the buffer required by xrstor is accessible.\n\nIn this case, xrstor tries to restore and accesses the unmapped area\nwhich results in a fault. But fault_in_readable succeeds because buf +\nfx_sw-\u003exstate_size is within the still mapped area, so it goes back and\ntries xrstor again. It will spin in this loop forever.\n\nInstead, fault in the maximum size which can be touched by XRSTOR (taken\nfrom fpstate-\u003euser_size).\n\n[ dhansen: tweak subject / changelog ]",
  "id": "GHSA-fq97-hv4f-crm6",
  "modified": "2024-04-17T18:31:31Z",
  "published": "2024-02-26T18:30:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26603"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/627339cccdc9166792ecf96bc3c9f711a60ce996"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/627e28cbb65564e55008315d9e02fbb90478beda"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8bd3eee7720c14b59a206bd05b98d7586bccf99a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b2479ab426cef7ab79a13005650eff956223ced2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d877550eaf2dc9090d782864c96939397a3c6835"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/EZOU3745CWCDZ7EMKMXB2OEEIB5Q3IWM"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/OX4EWCYDZRTOEMC2C6OF7ZACAP23SUB5"
    }
  ],
  "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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