GHSA-57M3-P558-GHPC
Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33In the Linux kernel, the following vulnerability has been resolved:
net: microchip: vcap: fix races on the shared Super VCAP block
The VCAP instances on a chip are not independent, yet they are locked independently. On sparx5 and lan969x the IS0 and IS2 instances are backed by the same Super VCAP hardware block and share its cache and command registers: every access drives the shared VCAP_SUPER_CTRL register and moves data through the shared cache registers.
Accessing one instance therefore races with accessing another. The per-instance admin->lock cannot prevent this, as each instance takes a different lock.
The locking issue is mostly disguised by the fact that the core usage of the vcap api runs under rtnl. However, the full rule dump in debugfs decodes rules straight from hardware (a READ command followed by a cache read) and runs outside rtnl, so it races a concurrent tc-flower rule write to another Super VCAP instance.
Besides corrupting the dump, the read repopulates the shared cache between the writers cache fill and its write command, so the writer commits the wrong data and corrupts the hardware entry.
Introduce vcap_lock() and vcap_unlock() helpers and route every rule lock site in the VCAP API and its debugfs code through them. Replace the per-instance admin->lock with a single mutex in struct vcap_control that serializes access to all instances. The helpers reach it through a new admin->vctrl back-pointer, and the clients initialise and destroy the control lock instead of a per-instance one.
No path holds more than one instance lock, so collapsing them onto a single mutex cannot self-deadlock.
{
"affected": [],
"aliases": [
"CVE-2026-72340"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T06:22:07Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: microchip: vcap: fix races on the shared Super VCAP block\n\nThe VCAP instances on a chip are not independent, yet they are locked\nindependently. On sparx5 and lan969x the IS0 and IS2 instances are\nbacked by the same Super VCAP hardware block and share its cache and\ncommand registers: every access drives the shared VCAP_SUPER_CTRL\nregister and moves data through the shared cache registers.\n\nAccessing one instance therefore races with accessing another. The\nper-instance admin-\u003elock cannot prevent this, as each instance takes a\ndifferent lock.\n\nThe locking issue is mostly disguised by the fact that the core usage of\nthe vcap api runs under rtnl. However, the full rule dump in debugfs\ndecodes rules straight from hardware (a READ command followed by a cache\nread) and runs outside rtnl, so it races a concurrent tc-flower rule\nwrite to another Super VCAP instance.\n\nBesides corrupting the dump, the read repopulates the shared cache\nbetween the writers cache fill and its write command, so the writer\ncommits the wrong data and corrupts the hardware entry.\n\nIntroduce vcap_lock() and vcap_unlock() helpers and route every rule\nlock site in the VCAP API and its debugfs code through them. Replace the\nper-instance admin-\u003elock with a single mutex in struct vcap_control that\nserializes access to all instances. The helpers reach it through a new\nadmin-\u003evctrl back-pointer, and the clients initialise and destroy the\ncontrol lock instead of a per-instance one.\n\nNo path holds more than one instance lock, so collapsing them onto a\nsingle mutex cannot self-deadlock.",
"id": "GHSA-57m3-p558-ghpc",
"modified": "2026-08-17T06:33:24Z",
"published": "2026-08-15T06:32:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72340"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1e71a40d101547380590db582213c1f1dce1f041"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/49806bef9572a2e012610517bc14ed0a4db0d1fc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/786456d0a244bbd405dfc60e4de51f8b348b9cb1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/952928564cc5fdb06f92d7e25c6cd2e1d816362b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d7a8d500d7e42837bd8dce40cb52c97c6e8706a9"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
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Nomenclature
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.