GHSA-GCJX-RWW2-6XMM
Vulnerability from github – Published: 2026-10-28 12:31 – Updated: 2026-10-30 15:34In the Linux kernel, the following vulnerability has been resolved:
net: bcmgenet: unshare the skb before writing the control block
bcmgenet stores first_cb, last_cb and bytes_sent in the skb control block and reads them back on completion to free the skb and credit BQL. ether_setup() leaves IFF_TX_SKB_SHARING set, so the stack can resubmit a shared skb that is still in the ring. The next transmit overwrites last_cb, so the earlier slots complete without crediting their bytes and BQL stalls the queue until the watchdog resets it.
Unshare the skb before writing the control block.
Reproduce with pktgen in clone_skb mode, which hands the driver the same skb while earlier copies are still in the ring:
modprobe pktgen pg=/proc/net/pktgen echo "add_device eth0" > $pg/kpktgend_0 echo "dst_mac AA:BB:CC:DD:EE:FF" > $pg/eth0 echo "dst 192.0.2.1" > $pg/eth0 echo "clone_skb 8" > $pg/eth0 echo "count 0" > $pg/eth0 echo start > $pg/pgctrl & sleep 5 echo stop > $pg/pgctrl wait cat /sys/class/net/eth0/queues/tx-0/byte_queue_limits/inflight
inflight stays nonzero on the now idle queue. clone_skb 0 leaves it at zero.
{
"affected": [],
"aliases": [
"CVE-2026-99192"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-28T11:17:40Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bcmgenet: unshare the skb before writing the control block\n\nbcmgenet stores first_cb, last_cb and bytes_sent in the skb control\nblock and reads them back on completion to free the skb and credit BQL.\nether_setup() leaves IFF_TX_SKB_SHARING set, so the stack can resubmit\na shared skb that is still in the ring. The next transmit overwrites\nlast_cb, so the earlier slots complete without crediting their bytes\nand BQL stalls the queue until the watchdog resets it.\n\nUnshare the skb before writing the control block.\n\nReproduce with pktgen in clone_skb mode, which hands the driver the same\nskb while earlier copies are still in the ring:\n\n modprobe pktgen\n pg=/proc/net/pktgen\n echo \"add_device eth0\" \u003e $pg/kpktgend_0\n echo \"dst_mac AA:BB:CC:DD:EE:FF\" \u003e $pg/eth0\n echo \"dst 192.0.2.1\" \u003e $pg/eth0\n echo \"clone_skb 8\" \u003e $pg/eth0\n echo \"count 0\" \u003e $pg/eth0\n echo start \u003e $pg/pgctrl \u0026\n sleep 5\n echo stop \u003e $pg/pgctrl\n wait\n cat /sys/class/net/eth0/queues/tx-0/byte_queue_limits/inflight\n\ninflight stays nonzero on the now idle queue. clone_skb 0 leaves it at\nzero.",
"id": "GHSA-gcjx-rww2-6xmm",
"modified": "2026-10-30T15:34:24Z",
"published": "2026-10-28T12:31:07Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99192"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2e5fb9dd3aca0da534793ad8123b81deff396efe"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/40c04abcbc34e3afe338f41dae851ecbd72852ac"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7939ad3b4db9eadf45a64f0524f38337a9494672"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/89771ce4f8f67dcffae561b2ccac95c0f6e3aa01"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c13d43c92bc89f494592a60e624a7c0c42218d36"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e5aa07c62e4fda1206d314c9ea36d67cd6b95cad"
}
],
"schema_version": "1.4.0",
"severity": []
}
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