gsd-2021-47107
Vulnerability from gsd
Modified
2024-03-05 06:03
Details
In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new init_dirlist helper functions results in an underflow, allowing the XDR stream functions to write beyond the actual buffer. This calculation has always been suspect. NFSD has never sanity- checked the READDIR count argument, but the old entry encoders managed the problem correctly. With the commits below, entry encoding changed, exposing the underflow to the pointer arithmetic in xdr_reserve_space(). Modern NFS clients attempt to retrieve as much data as possible for each READDIR request. Also, we have no unit tests that exercise the behavior of READDIR at the lower bound of @count values. Thus this case was missed during testing.
Aliases


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{
  "gsd": {
    "metadata": {
      "exploitCode": "unknown",
      "remediation": "unknown",
      "reportConfidence": "confirmed",
      "type": "vulnerability"
    },
    "osvSchema": {
      "aliases": [
        "CVE-2021-47107"
      ],
      "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Fix READDIR buffer overflow\n\nIf a client sends a READDIR count argument that is too small (say,\nzero), then the buffer size calculation in the new init_dirlist\nhelper functions results in an underflow, allowing the XDR stream\nfunctions to write beyond the actual buffer.\n\nThis calculation has always been suspect. NFSD has never sanity-\nchecked the READDIR count argument, but the old entry encoders\nmanaged the problem correctly.\n\nWith the commits below, entry encoding changed, exposing the\nunderflow to the pointer arithmetic in xdr_reserve_space().\n\nModern NFS clients attempt to retrieve as much data as possible\nfor each READDIR request. Also, we have no unit tests that\nexercise the behavior of READDIR at the lower bound of @count\nvalues. Thus this case was missed during testing.",
      "id": "GSD-2021-47107",
      "modified": "2024-03-05T06:03:55.164664Z",
      "schema_version": "1.4.0"
    }
  },
  "namespaces": {
    "cve.org": {
      "CVE_data_meta": {
        "ASSIGNER": "cve@kernel.org",
        "ID": "CVE-2021-47107",
        "STATE": "PUBLIC"
      },
      "affects": {
        "vendor": {
          "vendor_data": [
            {
              "product": {
                "product_data": [
                  {
                    "product_name": "Linux",
                    "version": {
                      "version_data": [
                        {
                          "version_affected": "\u003c",
                          "version_name": "7f87fc2d34d4",
                          "version_value": "eabc0aab98e5"
                        },
                        {
                          "version_value": "not down converted",
                          "x_cve_json_5_version_data": {
                            "defaultStatus": "affected",
                            "versions": [
                              {
                                "status": "affected",
                                "version": "5.13"
                              },
                              {
                                "lessThan": "5.13",
                                "status": "unaffected",
                                "version": "0",
                                "versionType": "custom"
                              },
                              {
                                "lessThanOrEqual": "5.15.*",
                                "status": "unaffected",
                                "version": "5.15.12",
                                "versionType": "custom"
                              },
                              {
                                "lessThanOrEqual": "*",
                                "status": "unaffected",
                                "version": "5.16",
                                "versionType": "original_commit_for_fix"
                              }
                            ]
                          }
                        }
                      ]
                    }
                  }
                ]
              },
              "vendor_name": "Linux"
            }
          ]
        }
      },
      "data_format": "MITRE",
      "data_type": "CVE",
      "data_version": "4.0",
      "description": {
        "description_data": [
          {
            "lang": "eng",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Fix READDIR buffer overflow\n\nIf a client sends a READDIR count argument that is too small (say,\nzero), then the buffer size calculation in the new init_dirlist\nhelper functions results in an underflow, allowing the XDR stream\nfunctions to write beyond the actual buffer.\n\nThis calculation has always been suspect. NFSD has never sanity-\nchecked the READDIR count argument, but the old entry encoders\nmanaged the problem correctly.\n\nWith the commits below, entry encoding changed, exposing the\nunderflow to the pointer arithmetic in xdr_reserve_space().\n\nModern NFS clients attempt to retrieve as much data as possible\nfor each READDIR request. Also, we have no unit tests that\nexercise the behavior of READDIR at the lower bound of @count\nvalues. Thus this case was missed during testing."
          }
        ]
      },
      "generator": {
        "engine": "bippy-4986f5686161"
      },
      "problemtype": {
        "problemtype_data": [
          {
            "description": [
              {
                "lang": "eng",
                "value": "n/a"
              }
            ]
          }
        ]
      },
      "references": {
        "reference_data": [
          {
            "name": "https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885",
            "refsource": "MISC",
            "url": "https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885"
          },
          {
            "name": "https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72",
            "refsource": "MISC",
            "url": "https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72"
          }
        ]
      }
    },
    "nvd.nist.gov": {
      "cve": {
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Fix READDIR buffer overflow\n\nIf a client sends a READDIR count argument that is too small (say,\nzero), then the buffer size calculation in the new init_dirlist\nhelper functions results in an underflow, allowing the XDR stream\nfunctions to write beyond the actual buffer.\n\nThis calculation has always been suspect. NFSD has never sanity-\nchecked the READDIR count argument, but the old entry encoders\nmanaged the problem correctly.\n\nWith the commits below, entry encoding changed, exposing the\nunderflow to the pointer arithmetic in xdr_reserve_space().\n\nModern NFS clients attempt to retrieve as much data as possible\nfor each READDIR request. Also, we have no unit tests that\nexercise the behavior of READDIR at the lower bound of @count\nvalues. Thus this case was missed during testing."
          }
        ],
        "id": "CVE-2021-47107",
        "lastModified": "2024-03-05T13:41:01.900",
        "metrics": {},
        "published": "2024-03-04T19:15:18.793",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Awaiting Analysis"
      }
    }
  }
}


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