CVE-2026-52947 (GCVE-0-2026-52947)
Vulnerability from cvelistv5 – Published: 2026-06-24 16:26 – Updated: 2026-06-28 06:37
VLAI?
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:
<TASK>
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
...
</TASK>
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
sock_put(). As Simon Horman pointed out, the callers of qrtr_port_remove()
still hold a reference to the socket, so freeing the socket memory here
would lead to a subsequent UAF in the caller. Thus, the __sock_put() is
kept, but only repositioned to close the RCU race.)
Severity ?
7.8 (High)
Assigner
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux |
Affected:
bdabad3e363d825ddf9679dd431cca0b2c30f881 , < 2aa4c12723fe432e623462a3be42a197a128722b
(git)
Affected: bdabad3e363d825ddf9679dd431cca0b2c30f881 , < 03bfa95e452e2b6ccd76a332060ae4feaf5ad84d (git) Affected: bdabad3e363d825ddf9679dd431cca0b2c30f881 , < 474293d90880622fde9d2430fb0165767090f7b3 (git) Affected: bdabad3e363d825ddf9679dd431cca0b2c30f881 , < 2047c2aa0963bb2872fd722300a15bcb441a4c00 (git) Affected: bdabad3e363d825ddf9679dd431cca0b2c30f881 , < 7de2d447072be3b1a76793f034432338fc9c494b (git) Affected: bdabad3e363d825ddf9679dd431cca0b2c30f881 , < ab269990ed58143a92a263be1bee626d82ac03da (git) Affected: bdabad3e363d825ddf9679dd431cca0b2c30f881 , < 3b20ec8f31e8a6a6782243f473b0abd3463621df (git) Affected: bdabad3e363d825ddf9679dd431cca0b2c30f881 , < a2171131ecda1ed61a594a1eb715e75fdad0fef5 (git) |
|||||||
|
|||||||||
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"descriptions": [
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"lang": "en",
"value": "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 \u003cTASK\u003e\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 \u003c/TASK\u003e\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.)"
}
],
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"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
}
}
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"providerMetadata": {
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"url": "https://git.kernel.org/stable/c/a2171131ecda1ed61a594a1eb715e75fdad0fef5"
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"title": "net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove",
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"cveId": "CVE-2026-52947",
"datePublished": "2026-06-24T16:26:05.062Z",
"dateReserved": "2026-06-09T07:44:35.371Z",
"dateUpdated": "2026-06-28T06:37:05.590Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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