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CVE-2025-38255 (GCVE-0-2025-38255)

Vulnerability from cvelistv5 – Published: 2025-07-09 10:42 – Updated: 2026-05-11 21:24
VLAI
Title
lib/group_cpus: fix NULL pointer dereference from group_cpus_evenly()
Summary
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]
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 6a6dcae8f486c3f3298d0767d34505121c7b0b81 , < 64a99eff8dcf1f951a544e6058341b2b19a8fdbd (git)
Affected: 6a6dcae8f486c3f3298d0767d34505121c7b0b81 , < 29d39e0d5f16c060e32542b2cf351c09fd22b250 (git)
Affected: 6a6dcae8f486c3f3298d0767d34505121c7b0b81 , < 911ef2e8a7de5b2bae8ff11fb0bd01f699e6db65 (git)
Affected: 6a6dcae8f486c3f3298d0767d34505121c7b0b81 , < df831e97739405ecbaddb85516bc7d4d1c933d6b (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.3
Unaffected: 0 , < 6.3 (semver)
Unaffected: 6.6.96 , ≤ 6.6.* (semver)
Unaffected: 6.12.36 , ≤ 6.12.* (semver)
Unaffected: 6.15.5 , ≤ 6.15.* (semver)
Unaffected: 6.16 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlib/group_cpus: fix NULL pointer dereference from group_cpus_evenly()\n\nWhile testing null_blk with configfs, echo 0 \u003e poll_queues will trigger\nfollowing panic:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000010\nOops: Oops: 0000 [#1] SMP NOPTI\nCPU: 27 UID: 0 PID: 920 Comm: bash Not tainted 6.15.0-02023-gadbdb95c8696-dirty #1238 PREEMPT(undef)\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014\nRIP: 0010:__bitmap_or+0x48/0x70\nCall Trace:\n \u003cTASK\u003e\n __group_cpus_evenly+0x822/0x8c0\n group_cpus_evenly+0x2d9/0x490\n blk_mq_map_queues+0x1e/0x110\n null_map_queues+0xc9/0x170 [null_blk]\n blk_mq_update_queue_map+0xdb/0x160\n blk_mq_update_nr_hw_queues+0x22b/0x560\n nullb_update_nr_hw_queues+0x71/0xf0 [null_blk]\n nullb_device_poll_queues_store+0xa4/0x130 [null_blk]\n configfs_write_iter+0x109/0x1d0\n vfs_write+0x26e/0x6f0\n ksys_write+0x79/0x180\n __x64_sys_write+0x1d/0x30\n x64_sys_call+0x45c4/0x45f0\n do_syscall_64+0xa5/0x240\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nRoot cause is that numgrps is set to 0, and ZERO_SIZE_PTR is returned from\nkcalloc(), and later ZERO_SIZE_PTR will be deferenced.\n\nFix the problem by checking numgrps first in group_cpus_evenly(), and\nreturn NULL directly if numgrps is zero.\n\n[yukuai3@huawei.com: also fix the non-SMP version]"
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        "dateUpdated": "2026-05-11T21:24:15.704Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/df831e97739405ecbaddb85516bc7d4d1c933d6b"
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      ],
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    "datePublished": "2025-07-09T10:42:33.225Z",
    "dateReserved": "2025-04-16T04:51:23.997Z",
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    "nvd": "{\"cve\":{\"id\":\"CVE-2025-38255\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-07-09T11:15:27.767\",\"lastModified\":\"2026-06-17T09:16:29.493\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nlib/group_cpus: fix NULL pointer dereference from group_cpus_evenly()\\n\\nWhile testing null_blk with configfs, echo 0 \u003e poll_queues will trigger\\nfollowing panic:\\n\\nBUG: kernel NULL pointer dereference, address: 0000000000000010\\nOops: Oops: 0000 [#1] SMP NOPTI\\nCPU: 27 UID: 0 PID: 920 Comm: bash Not tainted 6.15.0-02023-gadbdb95c8696-dirty #1238 PREEMPT(undef)\\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014\\nRIP: 0010:__bitmap_or+0x48/0x70\\nCall Trace:\\n \u003cTASK\u003e\\n __group_cpus_evenly+0x822/0x8c0\\n group_cpus_evenly+0x2d9/0x490\\n blk_mq_map_queues+0x1e/0x110\\n null_map_queues+0xc9/0x170 [null_blk]\\n blk_mq_update_queue_map+0xdb/0x160\\n blk_mq_update_nr_hw_queues+0x22b/0x560\\n nullb_update_nr_hw_queues+0x71/0xf0 [null_blk]\\n nullb_device_poll_queues_store+0xa4/0x130 [null_blk]\\n configfs_write_iter+0x109/0x1d0\\n vfs_write+0x26e/0x6f0\\n ksys_write+0x79/0x180\\n __x64_sys_write+0x1d/0x30\\n x64_sys_call+0x45c4/0x45f0\\n do_syscall_64+0xa5/0x240\\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\\n\\nRoot cause is that numgrps is set to 0, and ZERO_SIZE_PTR is returned from\\nkcalloc(), and later ZERO_SIZE_PTR will be deferenced.\\n\\nFix the problem by checking numgrps first in group_cpus_evenly(), and\\nreturn NULL directly if numgrps is zero.\\n\\n[yukuai3@huawei.com: also fix the non-SMP version]\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: lib/group_cpus: correcci\u00f3n de la desreferencia de puntero NULL de group_cpus_evenly() Al probar null_blk con configfs, echo 0 \u0026gt; poll_queues activar\u00e1 el siguiente p\u00e1nico: ERROR: desreferencia de puntero NULL del kernel, direcci\u00f3n: 0000000000000010 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 27 UID: 0 PID: 920 Comm: bash No contaminado 6.15.0-02023-gadbdb95c8696-dirty #1238 PREEMPT(undef) Nombre del hardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:__bitmap_or+0x48/0x70 Rastreo de llamadas:  __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 La causa principal es que numgrps est\u00e1 establecido en 0 y se devuelve ZERO_SIZE_PTR desde kcalloc(); posteriormente, se aplicar\u00e1 ZERO_SIZE_PTR. Solucione el problema comprobando primero numgrps en group_cpus_evenly() y devolviendo NULL directamente si numgrps es cero. 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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-06-30T00:59:46+00:00",
      "cve": "CVE-2025-38255",
      "id": "CVE-2025-38255",
      "initial_release_date": "2025-07-09T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: lib/group_cpus: fix NULL pointer dereference from group_cpus_evenly()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-38255.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-11T02:01:30Z",
      "cve": "CVE-2025-38255",
      "id": "CVE-2025-38255",
      "initial_release_date": "2025-07-09T23:22:58Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "466",
      "product_status:known_not_affected": "338",
      "product_status:recommended": "472",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-38255",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-38255.json",
      "version": "54"
    }
  }
}



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