FKIE_CVE-2026-64140

Vulnerability from fkie_nvd - Published: 2026-07-19 16:17 - Updated: 2026-07-20 15:17
Severity
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix null pointer dereference in proc_show_files() When a SMB2 client opens a file with a durable v2 handle and then issues SMB2 SESSION_LOGOFF, session_fd_check() clears fp->tcon = NULL on the reconnectable file pointer but leaves the fp registered in global_ft.idr until the durable scavenger fires (up to fp->durable_timeout seconds later). During that window any read of /proc/fs/ksmbd/files (mode 0400) panics the kernel because proc_show_files() walks global_ft.idr and unconditionally dereferences fp->tcon->id with no NULL guard. Reproducer requires only a successful SMB2 SESSION_SETUP and a share configured with 'durable handles = yes'. KASAN report on mainline 70390501d194: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:proc_show_files+0x118/0x740 Call Trace: proc_show_files+0x118/0x740 seq_read_iter+0x4ef/0xe10 proc_reg_read_iter+0x1b7/0x280 ... Guard the dereference. A durable-disconnected fp legitimately has no tcon; report its tree id as 0 rather than oopsing.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8eab081627b67216d1c8f638b68289b500dc9a6b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/904901561e61a2b559070b20c74a8c95491f30aa
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/vfs_cache.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "8eab081627b67216d1c8f638b68289b500dc9a6b",
              "status": "affected",
              "version": "b38f99c1217ae04753340f0fdcd8f35bf56841dc",
              "versionType": "git"
            },
            {
              "lessThan": "904901561e61a2b559070b20c74a8c95491f30aa",
              "status": "affected",
              "version": "b38f99c1217ae04753340f0fdcd8f35bf56841dc",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/vfs_cache.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix null pointer dereference in proc_show_files()\n\nWhen a SMB2 client opens a file with a durable v2 handle and then issues\nSMB2 SESSION_LOGOFF, session_fd_check() clears fp-\u003etcon = NULL on the\nreconnectable file pointer but leaves the fp registered in global_ft.idr\nuntil the durable scavenger fires (up to fp-\u003edurable_timeout seconds\nlater).\n\nDuring that window any read of /proc/fs/ksmbd/files (mode 0400) panics\nthe kernel because proc_show_files() walks global_ft.idr and\nunconditionally dereferences fp-\u003etcon-\u003eid with no NULL guard.\n\nReproducer requires only a successful SMB2 SESSION_SETUP and a share\nconfigured with \u0027durable handles = yes\u0027. KASAN report on mainline\n70390501d194:\n\n  general protection fault, probably for non-canonical address\n  0xdffffc0000000000: 0000 [#1] SMP KASAN PTI\n  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n  RIP: 0010:proc_show_files+0x118/0x740\n  Call Trace:\n   proc_show_files+0x118/0x740\n   seq_read_iter+0x4ef/0xe10\n   proc_reg_read_iter+0x1b7/0x280\n   ...\n\nGuard the dereference. A durable-disconnected fp legitimately has no\ntcon; report its tree id as 0 rather than oopsing."
    }
  ],
  "id": "CVE-2026-64140",
  "lastModified": "2026-07-20T15:17:12.050",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-07-19T16:17:55.887",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8eab081627b67216d1c8f638b68289b500dc9a6b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/904901561e61a2b559070b20c74a8c95491f30aa"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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