{"id":"CVE-2025-37807","summary":"bpf: Fix kmemleak warning for percpu hashmap","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't 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'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.","modified":"2026-04-02T12:47:29.379990Z","published":"2025-05-08T06:26:06.296Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/37xxx/CVE-2025-37807.json","cna_assigner":"Linux"},"references":[{"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"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/37xxx/CVE-2025-37807.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-37807"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"824bd0ce6c7c43a9e1e210abf124958e54d88342"},{"fixed":"7758e308aeda1038aba1944f7302d34161b3effe"},{"fixed":"1f1c29aa1934177349c17e3c32e68ec38a7a56df"},{"fixed":"11ba7ce076e5903e7bdc1fd1498979c331b3c286"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-37807.json"}}],"schema_version":"1.7.5"}