GHSA-9W39-MW48-92GC
Vulnerability from github – Published: 2026-03-18 18:31 – Updated: 2026-09-08 09:35In the Linux kernel, the following vulnerability has been resolved:
net: add proper RCU protection to /proc/net/ptype
Yin Fengwei reported an RCU stall in ptype_seq_show() and provided a patch.
Real issue is that ptype_seq_next() and ptype_seq_show() violate RCU rules.
ptype_seq_show() runs under rcu_read_lock(), and reads pt->dev to get device name without any barrier.
At the same time, concurrent writers can remove a packet_type structure (which is correctly freed after an RCU grace period) and clear pt->dev without an RCU grace period.
Define ptype_iter_state to carry a dev pointer along seq_net_private:
struct ptype_iter_state { struct seq_net_private p; struct net_device *dev; // added in this patch };
We need to record the device pointer in ptype_get_idx() and ptype_seq_next() so that ptype_seq_show() is safe against concurrent pt->dev changes.
We also need to add full RCU protection in ptype_seq_next(). (Missing READ_ONCE() when reading list.next values)
Many thanks to Dong Chenchen for providing a repro.
{
"affected": [],
"aliases": [
"CVE-2026-23255"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-03-18T18:16:23Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: add proper RCU protection to /proc/net/ptype\n\nYin Fengwei reported an RCU stall in ptype_seq_show() and provided\na patch.\n\nReal issue is that ptype_seq_next() and ptype_seq_show() violate\nRCU rules.\n\nptype_seq_show() runs under rcu_read_lock(), and reads pt-\u003edev\nto get device name without any barrier.\n\nAt the same time, concurrent writers can remove a packet_type structure\n(which is correctly freed after an RCU grace period) and clear pt-\u003edev\nwithout an RCU grace period.\n\nDefine ptype_iter_state to carry a dev pointer along seq_net_private:\n\nstruct ptype_iter_state {\n\tstruct seq_net_private\tp;\n\tstruct net_device\t*dev; // added in this patch\n};\n\nWe need to record the device pointer in ptype_get_idx() and\nptype_seq_next() so that ptype_seq_show() is safe against\nconcurrent pt-\u003edev changes.\n\nWe also need to add full RCU protection in ptype_seq_next().\n(Missing READ_ONCE() when reading list.next values)\n\nMany thanks to Dong Chenchen for providing a repro.",
"id": "GHSA-9w39-mw48-92gc",
"modified": "2026-09-08T09:35:27Z",
"published": "2026-03-18T18:31:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23255"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/002a73470b56848e4c81efeaaedd471e92d66d8d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/589a530ae44d0c80f523fcfd1a15af8087f27d35"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dcefd3f0b9ed8288654c75254bdcee8e1085e861"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e974a10a52618f7f57a4bce173a0ed96acd4e5dc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f613e8b4afea0cd17c7168e8b00e25bc8d33175d"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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