bpf: Mark bpf prog stack with kmsan_unposion_memory in interpreter mode

{
  "id": "b4f3e433880c214115c6430962b3fe2141492b8cd7f0fee7f880ba19012ae17d",
  "url": "https://osv.dev/vulnerability/CVE-2024-42063",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "bpf: Mark bpf prog stack with kmsan_unposion_memory in interpreter mode",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: bpf: Mark bpf prog stack with kmsan_unposion_memory in interpreter mode syzbot reported uninit memory usages during map_{lookup,delete}_elem. ========== BUG: KMSAN: uninit-value in __dev_map_lookup_elem kernel/bpf/devmap.c:441 [inline] BUG: KMSAN: uninit-value in dev_map_lookup_elem+0xf3/0x170 kernel/bpf/devmap.c:796 __dev_map_lookup_elem kernel/bpf/devmap.c:441 [inline] dev_map_lookup_elem+0xf3/0x170 kernel/bpf/devmap.c:796 ____bpf_map_lookup_elem kernel/bpf/helpers.c:42 [inline] bpf_map_lookup_elem+0x5c/0x80 kernel/bpf/helpers.c:38 ___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997 __bpf_prog_run256+0xb5/0xe0 kernel/bpf/core.c:2237 ========== The reproducer should be in the interpreter mode. The C reproducer is trying to run the following bpf prog: 0: (18) r0 = 0x0 2: (18) r1 = map[id:49] 4: (b7) r8 = 16777216 5: (7b) *(u64 *)(r10 -8) = r8 6: (bf) r2 = r10 7: (07) r2 += -229 ^^^^^^^^^^ 8: (b7) r3 = 8 9: (b7) r4 = 0 10: (85) call dev_map_lookup_elem#1543472 11: (95) exit It is due to the \"void *key\" (r2) passed to the helper. bpf allows uninit stack memory access for bpf prog with the right privileges. This patch uses kmsan_unpoison_memory() to mark the stack as initialized. This should address different syzbot reports on the uninit \"void *key\" argument during map_{lookup,delete}_elem.",
    "evidence": "osv:CVE-2024-42063",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.97",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.37",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.9.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2024-42063",
      "aliases": [
        "CVE-2024-42063"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "bd4cf0ed331a275e9bf5a49e6d0fd55dffc551b8"
                },
                {
                  "fixed": "b30f3197a6cd080052d5d4973f9a6b479fd9fff5"
                },
                {
                  "fixed": "d812ae6e02bd6e6a9cd1fdb09519c2f33e875faf"
                },
                {
                  "fixed": "3189983c26108cf0990e5c46856dc9feb9470d12"
                },
                {
                  "fixed": "e8742081db7d01f980c6161ae1e8a1dbc1e30979"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-42063.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "3.15.0"
                },
                {
                  "fixed": "6.1.97"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.37"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.9.8"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-42063.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:26.480678830Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/3189983c26108cf0990e5c46856dc9feb9470d12",
        "https://git.kernel.org/stable/c/b30f3197a6cd080052d5d4973f9a6b479fd9fff5",
        "https://git.kernel.org/stable/c/d812ae6e02bd6e6a9cd1fdb09519c2f33e875faf",
        "https://git.kernel.org/stable/c/e8742081db7d01f980c6161ae1e8a1dbc1e30979",
        "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/42xxx/CVE-2024-42063.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-42063",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/42xxx/CVE-2024-42063.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-42063",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 492758,
  "published_at": "2024-07-29T15:52:28.533+00:00"
}