GHSA-34VW-87PM-JFG6
Vulnerability from github – Published: 2025-10-01 12:30 – Updated: 2025-10-01 12:30In the Linux kernel, the following vulnerability has been resolved:
libbpf: Use elf_getshdrnum() instead of e_shnum
This commit replace e_shnum with the elf_getshdrnum() helper to fix two oss-fuzz-reported heap-buffer overflow in __bpf_object__open. Both reports are incorrectly marked as fixed and while still being reproducible in the latest libbpf.
# clusterfuzz-testcase-minimized-bpf-object-fuzzer-5747922482888704 libbpf: loading object 'fuzz-object' from buffer libbpf: sec_cnt is 0 libbpf: elf: section(1) .data, size 0, link 538976288, flags 2020202020202020, type=2 libbpf: elf: section(2) .data, size 32, link 538976288, flags 202020202020ff20, type=1 ================================================================= ==13==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6020000000c0 at pc 0x0000005a7b46 bp 0x7ffd12214af0 sp 0x7ffd12214ae8 WRITE of size 4 at 0x6020000000c0 thread T0 SCARINESS: 46 (4-byte-write-heap-buffer-overflow-far-from-bounds) #0 0x5a7b45 in bpf_object__elf_collect /src/libbpf/src/libbpf.c:3414:24 #1 0x5733c0 in bpf_object_open /src/libbpf/src/libbpf.c:7223:16 #2 0x5739fd in bpf_object__open_mem /src/libbpf/src/libbpf.c:7263:20 ...
The issue lie in libbpf's direct use of e_shnum field in ELF header as the section header count. Where as libelf implemented an extra logic that, when e_shnum == 0 && e_shoff != 0, will use sh_size member of the initial section header as the real section header count (part of ELF spec to accommodate situation where section header counter is larger than SHN_LORESERVE).
The above inconsistency lead to libbpf writing into a zero-entry calloc area. So intead of using e_shnum directly, use the elf_getshdrnum() helper provided by libelf to retrieve the section header counter into sec_cnt.
{
"affected": [],
"aliases": [
"CVE-2022-50450"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-10-01T12:15:37Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nlibbpf: Use elf_getshdrnum() instead of e_shnum\n\nThis commit replace e_shnum with the elf_getshdrnum() helper to fix two\noss-fuzz-reported heap-buffer overflow in __bpf_object__open. Both\nreports are incorrectly marked as fixed and while still being\nreproducible in the latest libbpf.\n\n # clusterfuzz-testcase-minimized-bpf-object-fuzzer-5747922482888704\n libbpf: loading object \u0027fuzz-object\u0027 from buffer\n libbpf: sec_cnt is 0\n libbpf: elf: section(1) .data, size 0, link 538976288, flags 2020202020202020, type=2\n libbpf: elf: section(2) .data, size 32, link 538976288, flags 202020202020ff20, type=1\n =================================================================\n ==13==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6020000000c0 at pc 0x0000005a7b46 bp 0x7ffd12214af0 sp 0x7ffd12214ae8\n WRITE of size 4 at 0x6020000000c0 thread T0\n SCARINESS: 46 (4-byte-write-heap-buffer-overflow-far-from-bounds)\n #0 0x5a7b45 in bpf_object__elf_collect /src/libbpf/src/libbpf.c:3414:24\n #1 0x5733c0 in bpf_object_open /src/libbpf/src/libbpf.c:7223:16\n #2 0x5739fd in bpf_object__open_mem /src/libbpf/src/libbpf.c:7263:20\n ...\n\nThe issue lie in libbpf\u0027s direct use of e_shnum field in ELF header as\nthe section header count. Where as libelf implemented an extra logic\nthat, when e_shnum == 0 \u0026\u0026 e_shoff != 0, will use sh_size member of the\ninitial section header as the real section header count (part of ELF\nspec to accommodate situation where section header counter is larger\nthan SHN_LORESERVE).\n\nThe above inconsistency lead to libbpf writing into a zero-entry calloc\narea. So intead of using e_shnum directly, use the elf_getshdrnum()\nhelper provided by libelf to retrieve the section header counter into\nsec_cnt.",
"id": "GHSA-34vw-87pm-jfg6",
"modified": "2025-10-01T12:30:28Z",
"published": "2025-10-01T12:30:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-50450"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/51deedc9b8680953437dfe359e5268120de10e30"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/622ff59742fe7bf53c06a57332040fa0e08b8242"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/854f8c61422053f71e3cf0c4abf757c8aa5c748d"
}
],
"schema_version": "1.4.0",
"severity": []
}
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