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arm64/fpsimd: signal: Forbid non-streaming SVE payload on SME-only systems

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: arm64/fpsimd: signal: Forbid non-streaming SVE payload on SME-only systems When system_supports_sme() is true but system_supports_sve() is false, restoring a specifically crafted SVE signal context can result in the task erroneously having non-streaming SVE state. Subsequent attempts to manipulate the task's FPSIMD/SVE/SME state can result in a variety of problems, including fatal EL1 UNDEFs. In such configurations, the kernel always creates an SVE signal context when delivering a signal, and this can only be in one of two states: (1) SVE_SIG_FLAG_SM is set, and an SVE payload is present containing streaming mode SVE state. The recorded VL is the task's live streaming VL. (2) SVE_SIG_FLAG_SM is clear, and an SVE payload is not present. The FPSIMD context contains the non-streaming mode FPSIMD state. The recorded VL is 0. Currently restore_sve_fpsimd_context() correctly rejects cases where SVE_SIG_FLAG_SM is set and an SVE payload is not present, but fails to reject cases where SVE_SIG_FLAG_SM is clear and an SVE payload is present. Consequently, restore_sve_fpsimd_context() can place the task in a state where it has non-streaming SVE state even when this is not supported by HW. For example, this can cause a later EL1 UNDEF when the kernel attempts to restore the task's ZCR_EL1 value: | # ./sme-sigcontext-to-sve | Internal error: Oops - Undefined instruction: 0000000002000000 [#1] SMP | Modules linked in: | CP

Announced Source revision 1
Original source ↗

CVE-2026-98745

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-98745

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033",
        "lessThan": "052acee9880114879b5c221fc8dad69b786d0938",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033",
        "lessThan": "f2338929c7663859c0c74dd6fef2c0245066f845",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033",
        "lessThan": "2bce6f006cfe0b60e8249fd8d51396d99355cba3",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033",
        "lessThan": "88c1c611552b24658eb61244086691c02be2013b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033",
        "lessThan": "e060d9069b49fe55f38057dfe592068014652671",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "05458ee3ff82b31a4564836a84ef20d6c233dfc7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6.1.7",
        "lessThan": "6.2",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "arch/arm64/kernel/signal.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "6.2"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "6.2",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.113",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.56",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.10",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "arch/arm64/kernel/signal.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-98745

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#48943 · Revision 1
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Publisher date
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