ghsa-5hjg-m862-88fc
Vulnerability from github
Published
2024-07-30 09:32
Modified
2024-08-05 21:31
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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.

Show details on source website

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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'.]\n\nGCC warns that `val' 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' 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: "2024-08-05T21:31:19Z",
   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",
      },
   ],
   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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