UnratedFix available

bpf: Avoid uninitialized value in BPF_CORE_READ_BITFIELD

Type: advisorySources: OSV

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.

Products: Kernel
Affected versions: Not specified
Fixed versions: 5.10.222, 5.15.163, 6.1.98, 6.6.39, 6.9.9
CVEs: CVE-2024-42161
Confirmed fixed CVEs: Not specified
Updated in this feed: 4 Nov 2026, 13:28 UTC · Revision 1

Source evidence

bpf: Avoid uninitialized value in BPF_CORE_READ_BITFIELD

core-osv · Original source

Published 30 Jul 2024, 07:47 UTC

osv:CVE-2024-42161

Kernel

Fixed versions: 5.10.222, 5.15.163, 6.1.98, 6.6.39, 6.9.9

Complete source record

{
  "id": "b7234ed90b713f1180548e0c8c977680f2a3bf45e823a3bc8f86eb0f3a5835f3",
  "url": "https://osv.dev/vulnerability/CVE-2024-42161",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "bpf: Avoid uninitialized value in BPF_CORE_READ_BITFIELD",
    "summary": "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.",
    "evidence": "osv:CVE-2024-42161",
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      ],
      "modified": "2026-10-28T02:30:36.296508103Z",
      "provider": "osv",
      "references": [
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  "source_id": "core-osv",
  "document_id": 503133,
  "published_at": "2024-07-30T07:47:03.136+00:00"
}