GHSA-73CW-J3WH-RF6G
Vulnerability from github – Published: 2025-05-08 09:30 – Updated: 2025-11-10 18:30In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix kmemleak warning for percpu hashmap
Vlad Poenaru reported the following kmemleak issue:
unreferenced object 0x606fd7c44ac8 (size 32): backtrace (crc 0): pcpu_alloc_noprof+0x730/0xeb0 bpf_map_alloc_percpu+0x69/0xc0 prealloc_init+0x9d/0x1b0 htab_map_alloc+0x363/0x510 map_create+0x215/0x3a0 __sys_bpf+0x16b/0x3e0 __x64_sys_bpf+0x18/0x20 do_syscall_64+0x7b/0x150 entry_SYSCALL_64_after_hwframe+0x4b/0x53
Further investigation shows the reason is due to not 8-byte aligned store of percpu pointer in htab_elem_set_ptr(): (void __percpu *)(l->key + key_size) = pptr;
Note that the whole htab_elem alignment is 8 (for x86_64). If the key_size is 4, that means pptr is stored in a location which is 4 byte aligned but not 8 byte aligned. In mm/kmemleak.c, scan_block() scans the memory based on 8 byte stride, so it won't detect above pptr, hence reporting the memory leak.
In htab_map_alloc(), we already have
htab->elem_size = sizeof(struct htab_elem) +
round_up(htab->map.key_size, 8);
if (percpu)
htab->elem_size += sizeof(void *);
else
htab->elem_size += round_up(htab->map.value_size, 8);
So storing pptr with 8-byte alignment won't cause any problem and can fix kmemleak too.
The issue can be reproduced with bpf selftest as well: 1. Enable CONFIG_DEBUG_KMEMLEAK config 2. Add a getchar() before skel destroy in test_hash_map() in prog_tests/for_each.c. The purpose is to keep map available so kmemleak can be detected. 3. run './test_progs -t for_each/hash_map &' and a kmemleak should be reported.
{
"affected": [],
"aliases": [
"CVE-2025-37807"
],
"database_specific": {
"cwe_ids": [
"CWE-401"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-05-08T07:15:51Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix kmemleak warning for percpu hashmap\n\nVlad Poenaru reported the following kmemleak issue:\n\n unreferenced object 0x606fd7c44ac8 (size 32):\n backtrace (crc 0):\n pcpu_alloc_noprof+0x730/0xeb0\n bpf_map_alloc_percpu+0x69/0xc0\n prealloc_init+0x9d/0x1b0\n htab_map_alloc+0x363/0x510\n map_create+0x215/0x3a0\n __sys_bpf+0x16b/0x3e0\n __x64_sys_bpf+0x18/0x20\n do_syscall_64+0x7b/0x150\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n\nFurther investigation shows the reason is due to not 8-byte aligned\nstore of percpu pointer in htab_elem_set_ptr():\n *(void __percpu **)(l-\u003ekey + key_size) = pptr;\n\nNote that the whole htab_elem alignment is 8 (for x86_64). If the key_size\nis 4, that means pptr is stored in a location which is 4 byte aligned but\nnot 8 byte aligned. In mm/kmemleak.c, scan_block() scans the memory based\non 8 byte stride, so it won\u0027t detect above pptr, hence reporting the memory\nleak.\n\nIn htab_map_alloc(), we already have\n\n htab-\u003eelem_size = sizeof(struct htab_elem) +\n round_up(htab-\u003emap.key_size, 8);\n if (percpu)\n htab-\u003eelem_size += sizeof(void *);\n else\n htab-\u003eelem_size += round_up(htab-\u003emap.value_size, 8);\n\nSo storing pptr with 8-byte alignment won\u0027t cause any problem and can fix\nkmemleak too.\n\nThe issue can be reproduced with bpf selftest as well:\n 1. Enable CONFIG_DEBUG_KMEMLEAK config\n 2. Add a getchar() before skel destroy in test_hash_map() in prog_tests/for_each.c.\n The purpose is to keep map available so kmemleak can be detected.\n 3. run \u0027./test_progs -t for_each/hash_map \u0026\u0027 and a kmemleak should be reported.",
"id": "GHSA-73cw-j3wh-rf6g",
"modified": "2025-11-10T18:30:31Z",
"published": "2025-05-08T09:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-37807"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/11ba7ce076e5903e7bdc1fd1498979c331b3c286"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1f1c29aa1934177349c17e3c32e68ec38a7a56df"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7758e308aeda1038aba1944f7302d34161b3effe"
}
],
"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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