GHSA-8GHR-4WGH-3JQ8
Vulnerability from github – Published: 2024-07-29 18:30 – Updated: 2025-11-04 00:31In 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 _bpfmap_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.
{
"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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