net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove_CVE-2026-52947

{
    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove\n\nIn qrtr_port_remove(), the socket reference count is decremented via\n__sock_put() before the port is removed from the qrtr_ports XArray and\nbefore the RCU grace period elapses.\n\nThis breaks the fundamental RCU update paradigm. It exposes a race\nwindow where a concurrent RCU reader (such as qrtr_reset_ports() or\nqrtr_port_lookup()) can obtain a pointer to the socket from the XArray,\nand attempt to call sock_hold() on a socket whose reference count has\nalready dropped to zero.\n\nThis exact race condition was hit during syzkaller fuzzing, leading to\nthe following refcount saturation warning and a potential Use-After-Free:\n\n  refcount_t: saturated; leaking memory.\n  WARNING: CPU: 3 PID: 1273 at lib/refcount.c:22 refcount_warn_saturate+0xae/0x1d0\n  Modules linked in: qrtr(+) bochs drm_shmem_helper ...\n  Call Trace:\n   <TASK>\n   qrtr_reset_ports net/qrtr/af_qrtr.c:768 [inline] [qrtr]\n   __qrtr_bind.isra.0+0x48b/0x570 net/qrtr/af_qrtr.c:805 [qrtr]\n   qrtr_bind+0x17d/0x210 net/qrtr/af_qrtr.c:901 [qrtr]\n   kernel_bind+0xe4/0x120 net/socket.c:3592\n   qrtr_ns_init+0x1a6/0x380 net/qrtr/ns.c:715 [qrtr]\n   qrtr_proto_init+0x3b/0xff0 net/qrtr/af_qrtr.c:169 [qrtr]\n   do_one_initcall+0xf5/0x5e0 init/main.c:1283\n   ...\n   </TASK>\n\nFix this by deferring the reference count decrement until after the\nxa_erase() and the synchronize_rcu() complete.\n\n(Note: The v1 of this patch incorrectly replaced __sock_put() with\nsock_put(). As Simon Horman pointed out, the callers of qrtr_port_remove()\nstill hold a reference to the socket, so freeing the socket memory here\nwould lead to a subsequent UAF in the caller. Thus, the __sock_put() is\nkept, but only repositioned to close the RCU race.)",
    "published": "2026-06-24T16:26:05.062Z",
    "modified": "2026-06-28T06:37:05.590Z",
    "type": "cve",
    "title": "net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/2aa4c12723fe432e623462a3be42a197a128722b\nhttps://git.kernel.org/stable/c/03bfa95e452e2b6ccd76a332060ae4feaf5ad84d\nhttps://git.kernel.org/stable/c/474293d90880622fde9d2430fb0165767090f7b3\nhttps://git.kernel.org/stable/c/2047c2aa0963bb2872fd722300a15bcb441a4c00\nhttps://git.kernel.org/stable/c/7de2d447072be3b1a76793f034432338fc9c494b\nhttps://git.kernel.org/stable/c/ab269990ed58143a92a263be1bee626d82ac03da\nhttps://git.kernel.org/stable/c/3b20ec8f31e8a6a6782243f473b0abd3463621df\nhttps://git.kernel.org/stable/c/a2171131ecda1ed61a594a1eb715e75fdad0fef5",
    "id": "CVE-2026-52947",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "Linux Linux bdabad3e363d825ddf9679dd431cca0b2c30f881\nLinux Linux bdabad3e363d825ddf9679dd431cca0b2c30f881\nLinux Linux bdabad3e363d825ddf9679dd431cca0b2c30f881\nLinux Linux bdabad3e363d825ddf9679dd431cca0b2c30f881\nLinux Linux bdabad3e363d825ddf9679dd431cca0b2c30f881\nLinux Linux bdabad3e363d825ddf9679dd431cca0b2c30f881\nLinux Linux bdabad3e363d825ddf9679dd431cca0b2c30f881\nLinux Linux bdabad3e363d825ddf9679dd431cca0b2c30f881\nLinux Linux 4.7",
    "sourceHref": "",
    "cvss": {
        "score": 7.8,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
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        "baseScore": 0,
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        "privilegesRequired": "",
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        "scope": "",
        "confidentialityImpact": "",
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        "cvssV3": {
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    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Linux",
    "version": "bdabad3e363d825ddf9679dd431cca0b2c30f881",
    "vendor": "Linux",
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    "ai_score": 0
}