net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove

{
  "id": "94a7b40bf406d6ac06a50f1648bdc601b8f83b3c108128fb7b292009e1404ed4",
  "url": "https://osv.dev/vulnerability/CVE-2026-52947",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove In qrtr_port_remove(), the socket reference count is decremented via __sock_put() before the port is removed from the qrtr_ports XArray and before the RCU grace period elapses. This breaks the fundamental RCU update paradigm. It exposes a race window where a concurrent RCU reader (such as qrtr_reset_ports() or qrtr_port_lookup()) can obtain a pointer to the socket from the XArray, and attempt to call sock_hold() on a socket whose reference count has already dropped to zero. This exact race condition was hit during syzkaller fuzzing, leading to the following refcount saturation warning and a potential Use-After-Free: refcount_t: saturated; leaking memory. WARNING: CPU: 3 PID: 1273 at lib/refcount.c:22 refcount_warn_saturate+0xae/0x1d0 Modules linked in: qrtr(+) bochs drm_shmem_helper ... Call Trace: qrtr_reset_ports net/qrtr/af_qrtr.c:768 [inline] [qrtr] __qrtr_bind.isra.0+0x48b/0x570 net/qrtr/af_qrtr.c:805 [qrtr] qrtr_bind+0x17d/0x210 net/qrtr/af_qrtr.c:901 [qrtr] kernel_bind+0xe4/0x120 net/socket.c:3592 qrtr_ns_init+0x1a6/0x380 net/qrtr/ns.c:715 [qrtr] qrtr_proto_init+0x3b/0xff0 net/qrtr/af_qrtr.c:169 [qrtr] do_one_initcall+0xf5/0x5e0 init/main.c:1283 ... Fix this by deferring the reference count decrement until after the xa_erase() and the synchronize_rcu() complete. (Note: The v1 of this patch incorrectly replaced __sock_put() with so",
    "evidence": "osv:CVE-2026-52947",
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      "modified": "2026-10-28T02:30:29.204901856Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-784472.html",
        "https://git.kernel.org/stable/c/03bfa95e452e2b6ccd76a332060ae4feaf5ad84d",
        "https://git.kernel.org/stable/c/2047c2aa0963bb2872fd722300a15bcb441a4c00",
        "https://git.kernel.org/stable/c/2aa4c12723fe432e623462a3be42a197a128722b",
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        "https://git.kernel.org/stable/c/ab269990ed58143a92a263be1bee626d82ac03da",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52947.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-52947",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
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        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52947.json"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
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  "source_id": "core-osv",
  "document_id": 496278,
  "published_at": "2026-06-24T16:26:05.062+00:00"
}