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

Vulnerability from cvelistv5 – Published: 2025-08-16 11:12 – Updated: 2026-07-30 05:54
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
References
Impacted products
Vendor Product Version
Linux Linux Affected: ee4cdf7ba857a894ad1650d6ab77669cbbfa329e , < 87dcc7e33fc3dcb8ed32333cec016528b5bb6ce4 (git)
Affected: ee4cdf7ba857a894ad1650d6ab77669cbbfa329e , < f0dd353d47f7051afa98c6c60c7486831eb1a410 (git)
Affected: ee4cdf7ba857a894ad1650d6ab77669cbbfa329e , < 43e7e284fc77b710d899569360ea46fa3374ae22 (git)
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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)
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{
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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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    "cveId": "CVE-2025-38523",
    "datePublished": "2025-08-16T11:12:17.254Z",
    "dateReserved": "2025-04-16T04:51:24.023Z",
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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.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/smb/client/smbdirect.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"ee4cdf7ba857a894ad1650d6ab77669cbbfa329e\",\"lessThan\":\"87dcc7e33fc3dcb8ed32333cec016528b5bb6ce4\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"ee4cdf7ba857a894ad1650d6ab77669cbbfa329e\",\"lessThan\":\"f0dd353d47f7051afa98c6c60c7486831eb1a410\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"ee4cdf7ba857a894ad1650d6ab77669cbbfa329e\",\"lessThan\":\"43e7e284fc77b710d899569360ea46fa3374ae22\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/smb/client/smbdirect.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.12\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.12\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.36\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.15.8\",\"lessThanOrEqual\":\"6.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.16\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-1188\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.12\",\"versionEndExcluding\":\"6.12.36\",\"matchCriteriaId\":\"64471BC5-89E0-43B3-8318-2D7EFF377CBD\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.15.8\",\"matchCriteriaId\":\"C7AFE5B0-F3B1-4D30-B8BF-EDA0385C4746\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.16:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"6D4894DB-CCFE-4602-B1BF-3960B2E19A01\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.16:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"09709862-E348-4378-8632-5A7813EDDC86\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.16:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"415BF58A-8197-43F5-B3D7-D1D63057A26E\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/43e7e284fc77b710d899569360ea46fa3374ae22\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/87dcc7e33fc3dcb8ed32333cec016528b5bb6ce4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/f0dd353d47f7051afa98c6c60c7486831eb1a410\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-30T09:04:15+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": "198",
      "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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