CVE-2025-37807 Affecting kernel-rt-modules-core package, versions *


Severity

Recommended
medium

Based on CentOS security rating.

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  • Snyk IDSNYK-CENTOS9-KERNELRTMODULESCORE-10089786
  • published9 May 2025
  • disclosed8 May 2025

Introduced: 8 May 2025

NewCVE-2025-37807  (opens in a new tab)

How to fix?

There is no fixed version for Centos:9 kernel-rt-modules-core.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-modules-core package and not the kernel-rt-modules-core package as distributed by Centos. See How to fix? for Centos:9 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1