CVE-2026-90359 (GCVE-0-2026-90359)
Vulnerability from cvelistv5
Published
2026-09-17 16:09
Modified
2026-10-21 12:51
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Reject >8 byte return values on return-reading trampoline paths btf_distill_func_proto() builds the function model used for the fentry/fexit/fmod_ret/fsession trampolines and struct_ops. It has accepted a 16-byte __int128 return value since the trampoline was introduced: __get_type_size() returns the integer's type size, and the return-type check only rejected ret < 0. But the BPF trampoline preserves only 8 bytes of the return value (RAX on x86, i.e. R0). For an attach type that reads the target's return value the second half (RDX / R3) is neither saved nor restored, so a program attached to a function returning a 16-byte value corrupts the value seen by the real caller and itself observes only half of it. struct_ops trampolines have the same limitation. This affects the attach types that read the target's return value: fexit, fmod_ret and fsession (plus the _multi variants of fexit and fsession), and struct_ops. fentry/fentry_multi run before the target returns and are unaffected. Reject a >8 byte return value for these attach types in bpf_check_attach_target() and bpf_check_attach_btf_id_multi(), and for struct_ops in bpf_struct_ops_desc_init().
References
Impacted products
Vendor Product Version
Linux Linux Version: fec56f5890d93fc2ed74166c397dc186b1c25951
Version: fec56f5890d93fc2ed74166c397dc186b1c25951
Version: fec56f5890d93fc2ed74166c397dc186b1c25951
Version: fec56f5890d93fc2ed74166c397dc186b1c25951
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/bpf_struct_ops.c",
            "kernel/bpf/verifier.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "lessThan": "de54ba33690d2dd3c4aa686c9693505644285b0b",
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              "version": "fec56f5890d93fc2ed74166c397dc186b1c25951",
              "versionType": "git"
            },
            {
              "lessThan": "9a9e902bd0556052534641f7d5f868c6dc4b84ae",
              "status": "affected",
              "version": "fec56f5890d93fc2ed74166c397dc186b1c25951",
              "versionType": "git"
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            {
              "lessThan": "d36ac53fc83baf843c51b7afd6d2471f36b713d8",
              "status": "affected",
              "version": "fec56f5890d93fc2ed74166c397dc186b1c25951",
              "versionType": "git"
            },
            {
              "lessThan": "c48796aa6c392cde93946e5d5a9a1f1b1cf72feb",
              "status": "affected",
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/bpf_struct_ops.c",
            "kernel/bpf/verifier.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.5"
            },
            {
              "lessThan": "5.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.114",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.57",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.114",
                  "versionStartIncluding": "5.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.57",
                  "versionStartIncluding": "5.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.6",
                  "versionStartIncluding": "5.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "5.5",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject \u003e8 byte return values on return-reading trampoline paths\n\nbtf_distill_func_proto() builds the function model used for the\nfentry/fexit/fmod_ret/fsession trampolines and struct_ops. It has\naccepted a 16-byte __int128 return value since the trampoline was\nintroduced: __get_type_size() returns the integer\u0027s type size, and the\nreturn-type check only rejected ret \u003c 0.\n\nBut the BPF trampoline preserves only 8 bytes of the return value (RAX on\nx86, i.e. R0). For an attach type that reads the target\u0027s return value the\nsecond half (RDX / R3) is neither saved nor restored, so a program\nattached to a function returning a 16-byte value corrupts the value seen\nby the real caller and itself observes only half of it. struct_ops\ntrampolines have the same limitation.\n\nThis affects the attach types that read the target\u0027s return value: fexit,\nfmod_ret and fsession (plus the _multi variants of fexit and fsession),\nand struct_ops. fentry/fentry_multi run before the target returns and are\nunaffected.\n\nReject a \u003e8 byte return value for these attach types in\nbpf_check_attach_target() and bpf_check_attach_btf_id_multi(), and for\nstruct_ops in bpf_struct_ops_desc_init()."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:51:16.798Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/de54ba33690d2dd3c4aa686c9693505644285b0b"
        },
        {
          "url": "https://git.kernel.org/stable/c/9a9e902bd0556052534641f7d5f868c6dc4b84ae"
        },
        {
          "url": "https://git.kernel.org/stable/c/d36ac53fc83baf843c51b7afd6d2471f36b713d8"
        },
        {
          "url": "https://git.kernel.org/stable/c/c48796aa6c392cde93946e5d5a9a1f1b1cf72feb"
        }
      ],
      "title": "bpf: Reject \u003e8 byte return values on return-reading trampoline paths",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90359",
    "datePublished": "2026-09-17T16:09:04.187Z",
    "dateReserved": "2026-09-11T19:38:34.806Z",
    "dateUpdated": "2026-10-21T12:51:16.798Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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