---
id: CVE-2025-37807
title: 'bpf: Fix kmemleak warning for percpu hashmap'
summary: |-
  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)…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 824bd0ce6c7c43a9e1e210abf124958e54d88342 <
    25014e3dfa6d2fb95c920b9e6b2f0b303baa4533
  - >-
    Linux >= 824bd0ce6c7c43a9e1e210abf124958e54d88342 <
    7758e308aeda1038aba1944f7302d34161b3effe
  - >-
    Linux >= 824bd0ce6c7c43a9e1e210abf124958e54d88342 <
    1f1c29aa1934177349c17e3c32e68ec38a7a56df
  - >-
    Linux >= 824bd0ce6c7c43a9e1e210abf124958e54d88342 <
    11ba7ce076e5903e7bdc1fd1498979c331b3c286
  - Linux 4.6
published: '2025-05-08'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T12:36:29.395Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-37807'
references:
  - url: 'https://git.kernel.org/stable/c/25014e3dfa6d2fb95c920b9e6b2f0b303baa4533'
  - url: 'https://git.kernel.org/stable/c/7758e308aeda1038aba1944f7302d34161b3effe'
  - url: 'https://git.kernel.org/stable/c/1f1c29aa1934177349c17e3c32e68ec38a7a56df'
  - url: 'https://git.kernel.org/stable/c/11ba7ce076e5903e7bdc1fd1498979c331b3c286'
tags:
  - cve.org
epss: 0.00247
epssPercentile: 0.15924
ingestedAt: '2026-10-21T12:48:53.710Z'
---

## Overview

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.

## Affected

- `Linux >= 824bd0ce6c7c43a9e1e210abf124958e54d88342 < 25014e3dfa6d2fb95c920b9e6b2f0b303baa4533`
- `Linux >= 824bd0ce6c7c43a9e1e210abf124958e54d88342 < 7758e308aeda1038aba1944f7302d34161b3effe`
- `Linux >= 824bd0ce6c7c43a9e1e210abf124958e54d88342 < 1f1c29aa1934177349c17e3c32e68ec38a7a56df`
- `Linux >= 824bd0ce6c7c43a9e1e210abf124958e54d88342 < 11ba7ce076e5903e7bdc1fd1498979c331b3c286`
- `Linux 4.6`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.