CVE-2025-38523 (GCVE-0-2025-38523)

Vulnerability from cvelistv5 – Published: 2025-08-16 11:12 – Updated: 2026-08-05 12:02
VLAI
Title
cifs: Fix the smbd_response slab to allow usercopy
Summary
In the Linux kernel, the following vulnerability has been resolved: cifs: Fix the smbd_response slab to allow usercopy The handling of received data in the smbdirect client code involves using copy_to_iter() to copy data from the smbd_reponse struct's packet trailer to a folioq buffer provided by netfslib that encapsulates a chunk of pagecache. If, however, CONFIG_HARDENED_USERCOPY=y, this will result in the checks then performed in copy_to_iter() oopsing with something like the following: CIFS: Attempting to mount //172.31.9.1/test CIFS: VFS: RDMA transport established usercopy: Kernel memory exposure attempt detected from SLUB object 'smbd_response_0000000091e24ea1' (offset 81, size 63)! ------------[ cut here ]------------ kernel BUG at mm/usercopy.c:102! ... RIP: 0010:usercopy_abort+0x6c/0x80 ... Call Trace: <TASK> __check_heap_object+0xe3/0x120 __check_object_size+0x4dc/0x6d0 smbd_recv+0x77f/0xfe0 [cifs] cifs_readv_from_socket+0x276/0x8f0 [cifs] cifs_read_from_socket+0xcd/0x120 [cifs] cifs_demultiplex_thread+0x7e9/0x2d50 [cifs] kthread+0x396/0x830 ret_from_fork+0x2b8/0x3b0 ret_from_fork_asm+0x1a/0x30 The problem is that the smbd_response slab's packet field isn't marked as being permitted for usercopy. Fix this by passing parameters to kmem_slab_create() to indicate that copy_to_iter() is permitted from the packet region of the smbd_response slab objects, less the header space.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6637 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: ee4cdf7ba857a894ad1650d6ab77669cbbfa329e , < 87dcc7e33fc3dcb8ed32333cec016528b5bb6ce4 (git)
Affected: ee4cdf7ba857a894ad1650d6ab77669cbbfa329e , < f0dd353d47f7051afa98c6c60c7486831eb1a410 (git)
Affected: ee4cdf7ba857a894ad1650d6ab77669cbbfa329e , < 43e7e284fc77b710d899569360ea46fa3374ae22 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.12
Unaffected: 0 , < 6.12 (semver)
Unaffected: 6.12.36 , ≤ 6.12.* (semver)
Unaffected: 6.15.8 , ≤ 6.15.* (semver)
Unaffected: 6.16 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: Fix the smbd_response slab to allow usercopy\n\nThe handling of received data in the smbdirect client code involves using\ncopy_to_iter() to copy data from the smbd_reponse struct\u0027s packet trailer\nto a folioq buffer provided by netfslib that encapsulates a chunk of\npagecache.\n\nIf, however, CONFIG_HARDENED_USERCOPY=y, this will result in the checks\nthen performed in copy_to_iter() oopsing with something like the following:\n\n CIFS: Attempting to mount //172.31.9.1/test\n CIFS: VFS: RDMA transport established\n usercopy: Kernel memory exposure attempt detected from SLUB object \u0027smbd_response_0000000091e24ea1\u0027 (offset 81, size 63)!\n ------------[ cut here ]------------\n kernel BUG at mm/usercopy.c:102!\n ...\n RIP: 0010:usercopy_abort+0x6c/0x80\n ...\n Call Trace:\n  \u003cTASK\u003e\n  __check_heap_object+0xe3/0x120\n  __check_object_size+0x4dc/0x6d0\n  smbd_recv+0x77f/0xfe0 [cifs]\n  cifs_readv_from_socket+0x276/0x8f0 [cifs]\n  cifs_read_from_socket+0xcd/0x120 [cifs]\n  cifs_demultiplex_thread+0x7e9/0x2d50 [cifs]\n  kthread+0x396/0x830\n  ret_from_fork+0x2b8/0x3b0\n  ret_from_fork_asm+0x1a/0x30\n\nThe problem is that the smbd_response slab\u0027s packet field isn\u0027t marked as\nbeing permitted for usercopy.\n\nFix this by passing parameters to kmem_slab_create() to indicate that\ncopy_to_iter() is permitted from the packet region of the smbd_response\nslab objects, less the header space."
          },
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            "lang": "es",
            "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: cifs: Arreglar el slab smbd_response para permitir usercopy El manejo de los datos recibidos en el c\u00f3digo del cliente smbdirect implica usar copy_to_iter() para copiar datos del tr\u00e1iler de paquetes de la estructura smbd_reponse a un b\u00fafer folioq proporcionado por netfslib que encapsula un trozo de pagecache. Sin embargo, si CONFIG_HARDENED_USERCOPY=y, esto dar\u00e1 como resultado que las comprobaciones realizadas en copy_to_iter() generen un error similar a lo siguiente: CIFS: Intentando montar //172.31.9.1/test CIFS: VFS: Transporte RDMA establecido usercopy: \u00a1Intento de exposici\u00f3n de memoria del kernel detectado desde el objeto SLUB \u0027smbd_response_0000000091e24ea1\u0027 (desplazamiento 81, tama\u00f1o 63)!-----------[ cut here ]------------ kernel BUG at mm/usercopy.c:102! ... RIP: 0010:usercopy_abort+0x6c/0x80 ... Call Trace:  __check_heap_object+0xe3/0x120 __check_object_size+0x4dc/0x6d0 smbd_recv+0x77f/0xfe0 [cifs] cifs_readv_from_socket+0x276/0x8f0 [cifs] cifs_read_from_socket+0xcd/0x120 [cifs] cifs_demultiplex_thread+0x7e9/0x2d50 [cifs] kthread+0x396/0x830 ret_from_fork+0x2b8/0x3b0 ret_from_fork_asm+0x1a/0x30 El problema es que la respuesta smbd_response El campo de paquete de slab no est\u00e1 marcado como permitido para copia de usuario. Se soluciona pasando par\u00e1metros a kmem_slab_create() para indicar que se permite copy_to_iter() desde la regi\u00f3n de paquete de los objetos slab smbd_response, menos el espacio de encabezado."
          }
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        "id": "CVE-2025-38523",
        "lastModified": "2026-07-30T06:23:23.710",
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        "vulnStatus": "Modified",
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                "value": "CWE-1188"
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    "redhat_vex": {
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      "current_release_date": "2026-11-05T15:02:27+00:00",
      "cve": "CVE-2025-38523",
      "id": "CVE-2025-38523",
      "initial_release_date": "2025-08-16T00:00:00+00:00",
      "product_status:fixed": "307",
      "product_status:known_not_affected": "199",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: cifs: Fix the smbd_response slab to allow usercopy",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-38523.json",
      "version": "3"
    }
  }
}



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  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.