lib/group_cpus: fix NULL pointer dereference from group_cpus_evenly() (Linux Linux)

CVE-2025-38255
MEDIUM 5.5

At a glance

Source
NVD
EPSS
EPSS 0.17 % · percentile 6 ()
State
PUBLISHED
Published
Updated
Assigner
Linux
NVD status
Analyzed

Description

In the Linux kernel, the following vulnerability has been resolved: lib/group_cpus: fix NULL pointer dereference from group_cpus_evenly() While testing null_blk with configfs, echo 0 > poll_queues will trigger following panic: BUG: kernel NULL pointer dereference, address: 0000000000000010 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 27 UID: 0 PID: 920 Comm: bash Not tainted 6.15.0-02023-gadbdb95c8696-dirty #1238 PREEMPT(undef) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:__bitmap_or+0x48/0x70 Call Trace: <TASK> __group_cpus_evenly+0x822/0x8c0 group_cpus_evenly+0x2d9/0x490 blk_mq_map_queues+0x1e/0x110 null_map_queues+0xc9/0x170 [null_blk] blk_mq_update_queue_map+0xdb/0x160 blk_mq_update_nr_hw_queues+0x22b/0x560 nullb_update_nr_hw_queues+0x71/0xf0 [null_blk] nullb_device_poll_queues_store+0xa4/0x130 [null_blk] configfs_write_iter+0x109/0x1d0 vfs_write+0x26e/0x6f0 ksys_write+0x79/0x180 __x64_sys_write+0x1d/0x30 x64_sys_call+0x45c4/0x45f0 do_syscall_64+0xa5/0x240 entry_SYSCALL_64_after_hwframe+0x76/0x7e Root cause is that numgrps is set to 0, and ZERO_SIZE_PTR is returned from kcalloc(), and later ZERO_SIZE_PTR will be deferenced. Fix the problem by checking numgrps first in group_cpus_evenly(), and return NULL directly if numgrps is zero. [yukuai3@huawei.com: also fix the non-SMP version]

Weaknesses (CWE)

  • CWE-476 — NULL Pointer Dereference

References

Scores

VersionScoreVectorScored by
CVSS 3.1MEDIUM 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HNVD · nvd@nist.gov (Primary)

European references

CERT-FR advisories

Affected configurations (NVD CPE)

Affected products

ProductVersions
Linux · Linuxaffected 6a6dcae8f486c3f3298d0767d34505121c7b0b81 < 64a99eff8dcf1f951a544e6058341b2b19a8fdbd ; affected 6a6dcae8f486c3f3298d0767d34505121c7b0b81 < 29d39e0d5f16c060e32542b2cf351c09fd22b250 ; affected 6a6dcae8f486c3f3298d0767d34505121c7b0b81 < 911ef2e8a7de5b2bae8ff11fb0bd01f699e6db65 ; affected 6a6dcae8f486c3f3298d0767d34505121c7b0b81 < df831e97739405ecbaddb85516bc7d4d1c933d6b
Linux · Linuxaffected 6.3 ; unaffected 0 < 6.3 ; unaffected 6.6.96 ≤ 6.6.* ; unaffected 6.12.36 ≤ 6.12.* ; unaffected 6.15.5 ≤ 6.15.* ; unaffected 6.16 ≤ *

Sources

SourceLicence
CVE List (CVEProject cvelistV5)CVE Program Terms of Use
EPSS (FIRST.org)FIRST — attribution requested
ENISA EUVDENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feedsPublic domain — this product uses data from the NVD API but is not endorsed or certified by the NVD