GHSA-478C-PQ6V-XX69
Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-19 18:31In the Linux kernel, the following vulnerability has been resolved:
net: ifb: report ethtool stats over num_tx_queues
ifb_dev_init() allocates dp->tx_private to dev->num_tx_queues entries via kzalloc_objs(*txp, dev->num_tx_queues). Both IFB per-queue RX and TX stats live in those entries: ifb_xmit() updates txp->rx_stats using the skb queue mapping, ifb_ri_tasklet() updates txp->tx_stats, and ifb_stats64() aggregates both over dev->num_tx_queues.
The ethtool stats callbacks instead size and walk the per-queue stats with dev->real_num_rx_queues and dev->real_num_tx_queues. With an asymmetric device where the RX queue count exceeds the TX queue count, for example:
ip link add name ifb10 numtxqueues 1 numrxqueues 8 type ifb
ethtool -S ifb10
ifb_get_ethtool_stats() indexes past the tx_private allocation and copies adjacent slab data through ETHTOOL_GSTATS.
Use dev->num_tx_queues consistently for the stats strings, the stats count, and the stats data walks. This reports one RX stats group and one TX stats group for each backing ifb_q_private entry, which is the queue set IFB can actually populate.
Reproduced under UML+KASAN at v7.1-rc2:
BUG: KASAN: slab-out-of-bounds in ifb_fill_stats_data+0x3c/0xae Read of size 8 at addr 0000000062dbd228 by task ethtool/36 ifb_fill_stats_data+0x3c/0xae ifb_get_ethtool_stats+0xc0/0x129 __dev_ethtool+0x1ca5/0x363c dev_ethtool+0x123/0x1b3 dev_ioctl+0x56c/0x744 sock_do_ioctl+0x15f/0x1b2 sock_ioctl+0x4d5/0x50a sys_ioctl+0xd8b/0xde9
With the patch applied, the same UML+KASAN repro is silent and ethtool -S ifb10 reports only the stats backed by the single allocated tx_private entry.
{
"affected": [],
"aliases": [
"CVE-2026-64121"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-19T16:17:53Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ifb: report ethtool stats over num_tx_queues\n\nifb_dev_init() allocates dp-\u003etx_private to dev-\u003enum_tx_queues\nentries via kzalloc_objs(*txp, dev-\u003enum_tx_queues). Both IFB\nper-queue RX and TX stats live in those entries: ifb_xmit() updates\ntxp-\u003erx_stats using the skb queue mapping, ifb_ri_tasklet() updates\ntxp-\u003etx_stats, and ifb_stats64() aggregates both over\ndev-\u003enum_tx_queues.\n\nThe ethtool stats callbacks instead size and walk the per-queue\nstats with dev-\u003ereal_num_rx_queues and dev-\u003ereal_num_tx_queues. With\nan asymmetric device where the RX queue count exceeds the TX queue\ncount, for example:\n\n ip link add name ifb10 numtxqueues 1 numrxqueues 8 type ifb\n ethtool -S ifb10\n\nifb_get_ethtool_stats() indexes past the tx_private allocation and\ncopies adjacent slab data through ETHTOOL_GSTATS.\n\nUse dev-\u003enum_tx_queues consistently for the stats strings, the\nstats count, and the stats data walks. This reports one RX stats\ngroup and one TX stats group for each backing ifb_q_private entry,\nwhich is the queue set IFB can actually populate.\n\nReproduced under UML+KASAN at v7.1-rc2:\n\n BUG: KASAN: slab-out-of-bounds in ifb_fill_stats_data+0x3c/0xae\n Read of size 8 at addr 0000000062dbd228 by task ethtool/36\n ifb_fill_stats_data+0x3c/0xae\n ifb_get_ethtool_stats+0xc0/0x129\n __dev_ethtool+0x1ca5/0x363c\n dev_ethtool+0x123/0x1b3\n dev_ioctl+0x56c/0x744\n sock_do_ioctl+0x15f/0x1b2\n sock_ioctl+0x4d5/0x50a\n sys_ioctl+0xd8b/0xde9\n\nWith the patch applied, the same UML+KASAN repro is silent and\nethtool -S ifb10 reports only the stats backed by the single\nallocated tx_private entry.",
"id": "GHSA-478c-pq6v-xx69",
"modified": "2026-07-19T18:31:52Z",
"published": "2026-07-19T18:31:52Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64121"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/16bd798cb6d8337d7c3eea1adc412f31b5181d5b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2638e1773904d7aa8f24c6e7fda2ed7d69df6fa4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/301a554e458e2f5ec47f2c336a7cb03b877f9fd6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5db89c99566fc4728cc92e941d8e1975711e24b5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6afdb8113cb007f9332f59a9b7fd45731b8a9de5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f8a5a76b4a683043c6eff2a060bcaa17f9316ad5"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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