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

Vulnerability from cvelistv5 – Published: 2025-07-09 10:42 – Updated: 2025-07-28 04:16
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 ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 6a6dcae8f486c3f3298d0767d34505121c7b0b81 , < 64a99eff8dcf1f951a544e6058341b2b19a8fdbd (git)
Affected: 6a6dcae8f486c3f3298d0767d34505121c7b0b81 , < 29d39e0d5f16c060e32542b2cf351c09fd22b250 (git)
Affected: 6a6dcae8f486c3f3298d0767d34505121c7b0b81 , < 911ef2e8a7de5b2bae8ff11fb0bd01f699e6db65 (git)
Affected: 6a6dcae8f486c3f3298d0767d34505121c7b0b81 , < df831e97739405ecbaddb85516bc7d4d1c933d6b (git)
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    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)
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{
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          "product": "Linux",
          "programFiles": [
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          "vendor": "Linux",
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                  "versionEndExcluding": "6.12.36",
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              "operator": "OR"
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      ],
      "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]"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-07-28T04:16:19.675Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/64a99eff8dcf1f951a544e6058341b2b19a8fdbd"
        },
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          "url": "https://git.kernel.org/stable/c/29d39e0d5f16c060e32542b2cf351c09fd22b250"
        },
        {
          "url": "https://git.kernel.org/stable/c/911ef2e8a7de5b2bae8ff11fb0bd01f699e6db65"
        },
        {
          "url": "https://git.kernel.org/stable/c/df831e97739405ecbaddb85516bc7d4d1c933d6b"
        }
      ],
      "title": "lib/group_cpus: fix NULL pointer dereference from group_cpus_evenly()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-38255",
    "datePublished": "2025-07-09T10:42:33.225Z",
    "dateReserved": "2025-04-16T04:51:23.997Z",
    "dateUpdated": "2025-07-28T04:16:19.675Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}


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