GHSA-8GHR-4WGH-3JQ8

Vulnerability from github – Published: 2024-07-29 18:30 – Updated: 2025-11-04 00:31
VLAI
Details

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.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2024-42063"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-908"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-07-29T16:15:06Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Mark bpf prog stack with kmsan_unposion_memory in interpreter mode\n\nsyzbot reported uninit memory usages during map_{lookup,delete}_elem.\n\n==========\nBUG: KMSAN: uninit-value in __dev_map_lookup_elem kernel/bpf/devmap.c:441 [inline]\nBUG: KMSAN: uninit-value in dev_map_lookup_elem+0xf3/0x170 kernel/bpf/devmap.c:796\n__dev_map_lookup_elem kernel/bpf/devmap.c:441 [inline]\ndev_map_lookup_elem+0xf3/0x170 kernel/bpf/devmap.c:796\n____bpf_map_lookup_elem kernel/bpf/helpers.c:42 [inline]\nbpf_map_lookup_elem+0x5c/0x80 kernel/bpf/helpers.c:38\n___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997\n__bpf_prog_run256+0xb5/0xe0 kernel/bpf/core.c:2237\n==========\n\nThe reproducer should be in the interpreter mode.\n\nThe C reproducer is trying to run the following bpf prog:\n\n    0: (18) r0 = 0x0\n    2: (18) r1 = map[id:49]\n    4: (b7) r8 = 16777216\n    5: (7b) *(u64 *)(r10 -8) = r8\n    6: (bf) r2 = r10\n    7: (07) r2 += -229\n            ^^^^^^^^^^\n\n    8: (b7) r3 = 8\n    9: (b7) r4 = 0\n   10: (85) call dev_map_lookup_elem#1543472\n   11: (95) exit\n\nIt is due to the \"void *key\" (r2) passed to the helper. bpf allows uninit\nstack memory access for bpf prog with the right privileges. This patch\nuses kmsan_unpoison_memory() to mark the stack as initialized.\n\nThis should address different syzbot reports on the uninit \"void *key\"\nargument during map_{lookup,delete}_elem.",
  "id": "GHSA-8ghr-4wgh-3jq8",
  "modified": "2025-11-04T00:31:05Z",
  "published": "2024-07-29T18:30:39Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-42063"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3189983c26108cf0990e5c46856dc9feb9470d12"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b30f3197a6cd080052d5d4973f9a6b479fd9fff5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d812ae6e02bd6e6a9cd1fdb09519c2f33e875faf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e8742081db7d01f980c6161ae1e8a1dbc1e30979"
    },
    {
      "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:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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