Bluetooth: l2cap: fix null-ptr-deref in l2cap_chan_timeout

{
  "id": "524d15b8bff7929ee1dead63e3c53ee31d11da6da4e2b4e1ce22b86dc629f79a",
  "url": "https://osv.dev/vulnerability/CVE-2024-27399",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Bluetooth: l2cap: fix null-ptr-deref in l2cap_chan_timeout",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: Bluetooth: l2cap: fix null-ptr-deref in l2cap_chan_timeout There is a race condition between l2cap_chan_timeout() and l2cap_chan_del(). When we use l2cap_chan_del() to delete the channel, the chan->conn will be set to null. But the conn could be dereferenced again in the mutex_lock() of l2cap_chan_timeout(). As a result the null pointer dereference bug will happen. The KASAN report triggered by POC is shown below: [ 472.074580] ================================================================== [ 472.075284] BUG: KASAN: null-ptr-deref in mutex_lock+0x68/0xc0 [ 472.075308] Write of size 8 at addr 0000000000000158 by task kworker/0:0/7 [ 472.075308] [ 472.075308] CPU: 0 PID: 7 Comm: kworker/0:0 Not tainted 6.9.0-rc5-00356-g78c0094a146b #36 [ 472.075308] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu4 [ 472.075308] Workqueue: events l2cap_chan_timeout [ 472.075308] Call Trace: [ 472.075308] [ 472.075308] dump_stack_lvl+0x137/0x1a0 [ 472.075308] print_report+0x101/0x250 [ 472.075308] ? __virt_addr_valid+0x77/0x160 [ 472.075308] ? mutex_lock+0x68/0xc0 [ 472.075308] kasan_report+0x139/0x170 [ 472.075308] ? mutex_lock+0x68/0xc0 [ 472.075308] kasan_check_range+0x2c3/0x2e0 [ 472.075308] mutex_lock+0x68/0xc0 [ 472.075308] l2cap_chan_timeout+0x181/0x300 [ 472.075308] process_one_work+0x5d2/0xe00 [ 472.075308] worker_thread+0xe1d/0x1660 [ 472.075308] ? pr_cont_work+0x5",
    "evidence": "osv:CVE-2024-27399",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "4.19.314",
            "evidence": "/affected/1/ranges"
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            "value": "5.4.276",
            "evidence": "/affected/1/ranges"
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            "evidence": "/affected/1/ranges"
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            "evidence": "/affected/1/ranges"
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            "evidence": "/affected/1/ranges"
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          {
            "value": "6.8.10",
            "evidence": "/affected/1/ranges"
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        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2024-27399",
      "aliases": [
        "CVE-2024-27399"
      ],
      "affected": [
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                  "fixed": "6466ee65e5b27161c846c73ef407f49dfa1bd1d9"
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                {
                  "fixed": "06acb75e7ed600d0bbf7bff5628aa8f24a97978c"
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                {
                  "fixed": "e97e16433eb4533083b096a3824b93a5ca3aee79"
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                {
                  "fixed": "8960ff650aec70485b40771cd8e6e8c4cb467d33"
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          "database_specific": {
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
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      ],
      "modified": "2026-10-28T02:30:42.312551845Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/06acb75e7ed600d0bbf7bff5628aa8f24a97978c",
        "https://git.kernel.org/stable/c/6466ee65e5b27161c846c73ef407f49dfa1bd1d9",
        "https://git.kernel.org/stable/c/8960ff650aec70485b40771cd8e6e8c4cb467d33",
        "https://git.kernel.org/stable/c/955b5b6c54d95b5e7444dfc81c95c8e013f27ac0",
        "https://git.kernel.org/stable/c/adf0398cee86643b8eacde95f17d073d022f782c",
        "https://git.kernel.org/stable/c/e137e2ba96e51902dc2878131823a96bf8e638ae",
        "https://git.kernel.org/stable/c/e97e16433eb4533083b096a3824b93a5ca3aee79",
        "https://git.kernel.org/stable/c/eb86f955488c39526534211f2610e48a5cf8ead4",
        "https://lists.debian.org/debian-lts-announce/2024/06/msg00019.html",
        "https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html",
        "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/DW2MIOIMOFUSNLHLRYX23AFR36BMKD65/",
        "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/OTB4HWU2PTVW5NEYHHLOCXDKG3PYA534/",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/27xxx/CVE-2024-27399.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-27399",
        "https://security.netapp.com/advisory/ntap-20240926-0001/",
        "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/2024/27xxx/CVE-2024-27399.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-27399",
        "evidence": "/id"
      }
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    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 509795,
  "published_at": "2024-05-13T10:24:57.045+00:00"
}