GHSA-HHGW-8M99-Q94G

Vulnerability from github – Published: 2026-10-18 18:31 – Updated: 2026-10-18 18:31
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

net: xps: reject an out of range traffic class

Only the entries below dev->num_tc are valid in dev->tc_to_txq[], and dev->prio_tc_map[] may only name classes below it. netdev_set_num_tc() lowers dev->num_tc without touching either array.

netdev_txq_to_tc() walks all TC_MAX_QUEUE slots and netdev_get_prio_tc_map() returns the entry as it stands, so a leftover entry is handed out as a traffic class >= dev->num_tc. Taking that class from netdev_txq_to_tc(), __netif_set_xps_queue() rejects only a negative one and indexes an XPS map sized for dev->num_tc classes:

tci = j * num_tc + tc;
RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);

attr_map[] holds nr_ids * num_tc entries and j runs over the ids named in the mask, so a class that is not below num_tc pushes tci past the end of the map for the last ids and the store overruns it.

Any caller that lowers num_tc leaves such entries behind, and mqprio_destroy() tears down with netdev_set_num_tc(dev, 0) rather than netdev_reset_tc(). After mqprio with 8 classes then 1, tc_to_txq[1..7] still describe txq 1..7. The splat is from an XPS write to txq 2 on a veth with 8 rx queues: attr_map[] has 8 * 1 entries, tci = j + 2, and j == 6 stores one past the end of the 88-byte map:

BUG: KASAN: slab-out-of-bounds in __netif_set_xps_queue (net/core/dev.c:2954) Write of size 8 at addr ffff88813016bc58 by task xps_oob/634 __netif_set_xps_queue (net/core/dev.c:2954) xps_rxqs_store (net/core/net-sysfs.c:1880) netdev_queue_attr_store (net/core/net-sysfs.c:1390) Allocated by task 634: __kmalloc_noprof (mm/slub.c:5439) __netif_set_xps_queue (net/core/dev.c:2937) The buggy address is located 0 bytes to the right of allocated 88-byte region [ffff88813016bc00, ffff88813016bc58)

Reject a class the map has no room for.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98567"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-18T16:17:08Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: xps: reject an out of range traffic class\n\nOnly the entries below dev-\u003enum_tc are valid in dev-\u003etc_to_txq[], and\ndev-\u003eprio_tc_map[] may only name classes below it. netdev_set_num_tc()\nlowers dev-\u003enum_tc without touching either array.\n\nnetdev_txq_to_tc() walks all TC_MAX_QUEUE slots and\nnetdev_get_prio_tc_map() returns the entry as it stands, so a leftover\nentry is handed out as a traffic class \u003e= dev-\u003enum_tc. Taking that\nclass from netdev_txq_to_tc(), __netif_set_xps_queue() rejects only a\nnegative one and indexes an XPS map sized for dev-\u003enum_tc classes:\n\n\ttci = j * num_tc + tc;\n\tRCU_INIT_POINTER(new_dev_maps-\u003eattr_map[tci], map);\n\nattr_map[] holds nr_ids * num_tc entries and j runs over the ids named\nin the mask, so a class that is not below num_tc pushes tci past the end\nof the map for the last ids and the store overruns it.\n\nAny caller that lowers num_tc leaves such entries behind, and\nmqprio_destroy() tears down with netdev_set_num_tc(dev, 0) rather than\nnetdev_reset_tc(). After mqprio with 8 classes then 1, tc_to_txq[1..7]\nstill describe txq 1..7. The splat is from an XPS write to txq 2 on a\nveth with 8 rx queues: attr_map[] has 8 * 1 entries, tci = j + 2, and\nj == 6 stores one past the end of the 88-byte map:\n\n  BUG: KASAN: slab-out-of-bounds in __netif_set_xps_queue (net/core/dev.c:2954)\n  Write of size 8 at addr ffff88813016bc58 by task xps_oob/634\n   __netif_set_xps_queue (net/core/dev.c:2954)\n   xps_rxqs_store (net/core/net-sysfs.c:1880)\n   netdev_queue_attr_store (net/core/net-sysfs.c:1390)\n  Allocated by task 634:\n   __kmalloc_noprof (mm/slub.c:5439)\n   __netif_set_xps_queue (net/core/dev.c:2937)\n  The buggy address is located 0 bytes to the right of\n   allocated 88-byte region [ffff88813016bc00, ffff88813016bc58)\n\nReject a class the map has no room for.",
  "id": "GHSA-hhgw-8m99-q94g",
  "modified": "2026-10-18T18:31:54Z",
  "published": "2026-10-18T18:31:54Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98567"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1cb8e40525a72c9f1e1cf94c68c172b3b9bbdc81"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2cc1c3977acbffc417fb5b57699d1df3dcffb5fd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4da3b7b8b50f3e2fde54a4c18a82a8e3f6223910"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6ea8f643053f33622f9116e4e1db58306ece45e3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/930318290d8509e864c015fe6c9239470b3c579c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/967e10f40a0c6732db299cbe001df0e859196055"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9e841723ba482d41ecbf90241c756a16cdfea949"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/eff227a3cb4d0089fbb85c73480bf8abf2e5ae7f"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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