CVE-2022-49886 (GCVE-0-2022-49886)

Vulnerability from cvelistv5 – Published: 2025-05-01 14:10 – Updated: 2025-05-04 08:47
VLAI?
Title
x86/tdx: Panic on bad configs that #VE on "private" memory access
Summary
In the Linux kernel, the following vulnerability has been resolved: x86/tdx: Panic on bad configs that #VE on "private" memory access All normal kernel memory is "TDX private memory". This includes everything from kernel stacks to kernel text. Handling exceptions on arbitrary accesses to kernel memory is essentially impossible because they can happen in horribly nasty places like kernel entry/exit. But, TDX hardware can theoretically _deliver_ a virtualization exception (#VE) on any access to private memory. But, it's not as bad as it sounds. TDX can be configured to never deliver these exceptions on private memory with a "TD attribute" called ATTR_SEPT_VE_DISABLE. The guest has no way to *set* this attribute, but it can check it. Ensure ATTR_SEPT_VE_DISABLE is set in early boot. panic() if it is unset. There is no sane way for Linux to run with this attribute clear so a panic() is appropriate. There's small window during boot before the check where kernel has an early #VE handler. But the handler is only for port I/O and will also panic() as soon as it sees any other #VE, such as a one generated by a private memory access. [ dhansen: Rewrite changelog and rebase on new tdx_parse_tdinfo(). Add Kirill's tested-by because I made changes since he wrote this. ]
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 9a22bf6debbf5169f750af53c7f86eb4e3cd6712 , < 895c168c8f78079f21ad50fead7593ffa352f795 (git)
Affected: 9a22bf6debbf5169f750af53c7f86eb4e3cd6712 , < 373e715e31bf4e0f129befe87613a278fac228d3 (git)
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    Linux Linux Affected: 5.19
Unaffected: 0 , < 5.19 (semver)
Unaffected: 6.0.8 , ≤ 6.0.* (semver)
Unaffected: 6.1 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "arch/x86/coco/tdx/tdx.c"
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                  "vulnerable": true
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/tdx: Panic on bad configs that #VE on \"private\" memory access\n\nAll normal kernel memory is \"TDX private memory\".  This includes\neverything from kernel stacks to kernel text.  Handling\nexceptions on arbitrary accesses to kernel memory is essentially\nimpossible because they can happen in horribly nasty places like\nkernel entry/exit.  But, TDX hardware can theoretically _deliver_\na virtualization exception (#VE) on any access to private memory.\n\nBut, it\u0027s not as bad as it sounds.  TDX can be configured to never\ndeliver these exceptions on private memory with a \"TD attribute\"\ncalled ATTR_SEPT_VE_DISABLE.  The guest has no way to *set* this\nattribute, but it can check it.\n\nEnsure ATTR_SEPT_VE_DISABLE is set in early boot.  panic() if it\nis unset.  There is no sane way for Linux to run with this\nattribute clear so a panic() is appropriate.\n\nThere\u0027s small window during boot before the check where kernel\nhas an early #VE handler. But the handler is only for port I/O\nand will also panic() as soon as it sees any other #VE, such as\na one generated by a private memory access.\n\n[ dhansen: Rewrite changelog and rebase on new tdx_parse_tdinfo().\n\t   Add Kirill\u0027s tested-by because I made changes since\n\t   he wrote this. ]"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-05-04T08:47:48.152Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/895c168c8f78079f21ad50fead7593ffa352f795"
        },
        {
          "url": "https://git.kernel.org/stable/c/373e715e31bf4e0f129befe87613a278fac228d3"
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      ],
      "title": "x86/tdx: Panic on bad configs that #VE on \"private\" memory access",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2022-49886",
    "datePublished": "2025-05-01T14:10:31.933Z",
    "dateReserved": "2025-05-01T14:05:17.241Z",
    "dateUpdated": "2025-05-04T08:47:48.152Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.1"
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