smb: client: fix UAF in smb2_reconnect_server()

{
  "id": "2468f32377535525133d6ef3c7cd2fd7c350ba0c23b6dd46c8ed9d9b66984afd",
  "url": "https://osv.dev/vulnerability/CVE-2024-35870",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "smb: client: fix UAF in smb2_reconnect_server()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: smb: client: fix UAF in smb2_reconnect_server() The UAF bug is due to smb2_reconnect_server() accessing a session that is already being teared down by another thread that is executing __cifs_put_smb_ses(). This can happen when (a) the client has connection to the server but no session or (b) another thread ends up setting @ses->ses_status again to something different than SES_EXITING. To fix this, we need to make sure to unconditionally set @ses->ses_status to SES_EXITING and prevent any other threads from setting a new status while we're still tearing it down. The following can be reproduced by adding some delay to right after the ipc is freed in __cifs_put_smb_ses() - which will give smb2_reconnect_server() worker a chance to run and then accessing @ses->ipc: kinit ... mount.cifs //srv/share /mnt/1 -o sec=krb5,nohandlecache,echo_interval=10 [disconnect srv] ls /mnt/1 &>/dev/null sleep 30 kdestroy [reconnect srv] sleep 10 umount /mnt/1 ... CIFS: VFS: Verify user has a krb5 ticket and keyutils is installed CIFS: VFS: \\\\srv Send error in SessSetup = -126 CIFS: VFS: Verify user has a krb5 ticket and keyutils is installed CIFS: VFS: \\\\srv Send error in SessSetup = -126 general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP NOPTI CPU: 3 PID: 50 Comm: kworker/3:1 Not tainted 6.9.0-rc2 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-1.fc39 04/01/201",
    "evidence": "osv:CVE-2024-35870",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.121",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.29",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.8.5",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "CVE-2024-35870",
      "aliases": [
        "CVE-2024-35870"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "introduced": "b327a717e506980399464e304e363f94f95eb7a1"
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                {
                  "fixed": "755fe68cd4b59e1d2a2dd3286177fd4404f57fed"
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                {
                  "fixed": "6202996a1c1887e83d0b3b0fcd86d0e5e6910ea0"
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                {
                  "fixed": "45f2beda1f1bc3d962ec07db1ccc3197c25499a5"
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                {
                  "fixed": "24a9799aa8efecd0eb55a75e35f9d8e6400063aa"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-35870.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "4.16.0"
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                {
                  "fixed": "6.1.121"
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            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.2.0"
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                {
                  "fixed": "6.6.29"
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              ]
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            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.8.5"
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              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-35870.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:26.444545138Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/24a9799aa8efecd0eb55a75e35f9d8e6400063aa",
        "https://git.kernel.org/stable/c/45f2beda1f1bc3d962ec07db1ccc3197c25499a5",
        "https://git.kernel.org/stable/c/6202996a1c1887e83d0b3b0fcd86d0e5e6910ea0",
        "https://git.kernel.org/stable/c/755fe68cd4b59e1d2a2dd3286177fd4404f57fed",
        "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/35xxx/CVE-2024-35870.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-35870",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/35xxx/CVE-2024-35870.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-35870",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 492750,
  "published_at": "2024-05-19T08:34:28.419+00:00"
}