GHSA-5HJG-M862-88FC

Vulnerability from github – Published: 2024-07-30 09:32 – Updated: 2025-11-04 00:31
VLAI
Details

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

bpf: Avoid uninitialized value in BPF_CORE_READ_BITFIELD

[Changes from V1: - Use a default branch in the switch statement to initialize `val'.]

GCC warns that `val' may be used uninitialized in the BPF_CRE_READ_BITFIELD macro, defined in bpf_core_read.h as:

[...]
unsigned long long val;                           \
[...]                                     \
switch (__CORE_RELO(s, field, BYTE_SIZE)) {               \
case 1: val = *(const unsigned char *)p; break;               \
case 2: val = *(const unsigned short *)p; break;              \
case 4: val = *(const unsigned int *)p; break;                \
case 8: val = *(const unsigned long long *)p; break;              \
    }                                         \
[...]
val;                                      \
}                                     \

This patch adds a default entry in the switch statement that sets `val' to zero in order to avoid the warning, and random values to be used in case __builtin_preserve_field_info returns unexpected values for BPF_FIELD_BYTE_SIZE.

Tested in bpf-next master. No regressions.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2024-42161"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-908"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-07-30T08:15:07Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Avoid uninitialized value in BPF_CORE_READ_BITFIELD\n\n[Changes from V1:\n - Use a default branch in the switch statement to initialize `val\u0027.]\n\nGCC warns that `val\u0027 may be used uninitialized in the\nBPF_CRE_READ_BITFIELD macro, defined in bpf_core_read.h as:\n\n\t[...]\n\tunsigned long long val;\t\t\t\t\t\t      \\\n\t[...]\t\t\t\t\t\t\t\t      \\\n\tswitch (__CORE_RELO(s, field, BYTE_SIZE)) {\t\t\t      \\\n\tcase 1: val = *(const unsigned char *)p; break;\t\t\t      \\\n\tcase 2: val = *(const unsigned short *)p; break;\t\t      \\\n\tcase 4: val = *(const unsigned int *)p; break;\t\t\t      \\\n\tcase 8: val = *(const unsigned long long *)p; break;\t\t      \\\n        }       \t\t\t\t\t\t\t      \\\n\t[...]\n\tval;\t\t\t\t\t\t\t\t      \\\n\t}\t\t\t\t\t\t\t\t      \\\n\nThis patch adds a default entry in the switch statement that sets\n`val\u0027 to zero in order to avoid the warning, and random values to be\nused in case __builtin_preserve_field_info returns unexpected values\nfor BPF_FIELD_BYTE_SIZE.\n\nTested in bpf-next master.\nNo regressions.",
  "id": "GHSA-5hjg-m862-88fc",
  "modified": "2025-11-04T00:31:08Z",
  "published": "2024-07-30T09:32:04Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-42161"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/009367099eb61a4fc2af44d4eb06b6b4de7de6db"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3364c2ed1c241989847f19cf83e3db903ce689e3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7e5471b5efebc30dd0bc035cda86693a5c73d45f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a21d76bd0b0d39518e9a4c19f6cf7c042a974aff"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b694989bb13ed5f166e633faa1eb0f21c6d261a6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ff941a8449e712eaf7efca1a13bfb9afd3d99fc2"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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