CVE-2025-37807
Full vulnerability record from the local CVENow database.
Description
In 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.
Severity
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-05-08 07:15:51.873000
Last modified
2026-10-30 13:17:57.910000
View original CVE JSON
{
"id": "CVE-2025-37807",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2025-05-08T07:15:51.873",
"lastModified": "2026-10-30T13:17:57.910",
"vulnStatus": "Modified",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "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->key + 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't detect above pptr, hence reporting the memory\nleak.\n\nIn htab_map_alloc(), we already have\n\n htab->elem_size = sizeof(struct htab_elem) +\n round_up(htab->map.key_size, 8);\n if (percpu)\n htab->elem_size += sizeof(void *);\n else\n htab->elem_size += round_up(htab->map.value_size, 8);\n\nSo storing pptr with 8-byte alignment won't 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 './test_progs -t for_each/hash_map &' and a kmemleak should be reported."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: bpf: Se corrige la advertencia de kmemleak para el mapa hash de percpu Vlad Poenaru informó el siguiente problema de kmemleak: objeto sin referencia 0x606fd7c44ac8 (tamaño 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 Una investigación más profunda muestra que la razón se debe a un almacenamiento no alineado de 8 bytes del puntero por CPU en htab_elem_set_ptr(): *(void __percpu **)(l->key + key_size) = pptr; Tenga en cuenta que la alineación completa de htab_elem es 8 (para x86_64). Si key_size es 4, significa que pptr se almacena en una ubicación que está alineada con 4 bytes pero no con 8 bytes. En mm/kmemleak.c, scan_block() escanea la memoria basándose en un paso de 8 bytes, por lo que no detectará por encima de pptr, por lo que informa la pérdida de memoria. En htab_map_alloc(), ya tenemos 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); Por lo tanto, almacenar pptr con alineación de 8 bytes no causará ningún problema y también puede solucionar la fuga de kmem. El problema también se puede reproducir con la autoprueba de BPF: 1. Habilite la configuración CONFIG_DEBUG_KMEMLEAK. 2. Añada un getchar() antes de skel destroy en test_hash_map() en prog_tests/for_each.c. El objetivo es mantener el mapa disponible para que se pueda detectar la fuga de kmem. 3. Ejecute './test_progs -t for_each/hash_map &' y se debería informar de una fuga de kmem."
}
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"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"attackVector": "LOCAL",
"attackComplexity": "LOW",
"privilegesRequired": "LOW",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 1.8,
"impactScore": 3.6
}
]
},
"weaknesses": [
{
"source": "[email protected]",
"type": "Primary",
"description": [
{
"lang": "en",
"value": "CWE-401"
}
]
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