ghsa-ccmh-pfgg-525g
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
sch_htb: make htb_deactivate() idempotent
Alan reported a NULL pointer dereference in htb_next_rb_node() after we made htb_qlen_notify() idempotent.
It turns out in the following case it introduced some regression:
htb_dequeue_tree(): |-> fq_codel_dequeue() |-> qdisc_tree_reduce_backlog() |-> htb_qlen_notify() |-> htb_deactivate() |-> htb_next_rb_node() |-> htb_deactivate()
For htb_next_rb_node(), after calling the 1st htb_deactivate(), the clprio[prio]->ptr could be already set to NULL, which means htb_next_rb_node() is vulnerable here.
For htb_deactivate(), although we checked qlen before calling it, in case of qlen==0 after qdisc_tree_reduce_backlog(), we may call it again which triggers the warning inside.
To fix the issues here, we need to:
1) Make htb_deactivate() idempotent, that is, simply return if we already call it before. 2) Make htb_next_rb_node() safe against ptr==NULL.
Many thanks to Alan for testing and for the reproducer.
{
"affected": [],
"aliases": [
"CVE-2025-37953"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-05-20T16:15:33Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsch_htb: make htb_deactivate() idempotent\n\nAlan reported a NULL pointer dereference in htb_next_rb_node()\nafter we made htb_qlen_notify() idempotent.\n\nIt turns out in the following case it introduced some regression:\n\nhtb_dequeue_tree():\n |-\u003e fq_codel_dequeue()\n |-\u003e qdisc_tree_reduce_backlog()\n |-\u003e htb_qlen_notify()\n |-\u003e htb_deactivate()\n |-\u003e htb_next_rb_node()\n |-\u003e htb_deactivate()\n\nFor htb_next_rb_node(), after calling the 1st htb_deactivate(), the\nclprio[prio]-\u003eptr could be already set to NULL, which means\nhtb_next_rb_node() is vulnerable here.\n\nFor htb_deactivate(), although we checked qlen before calling it, in\ncase of qlen==0 after qdisc_tree_reduce_backlog(), we may call it again\nwhich triggers the warning inside.\n\nTo fix the issues here, we need to:\n\n1) Make htb_deactivate() idempotent, that is, simply return if we\n already call it before.\n2) Make htb_next_rb_node() safe against ptr==NULL.\n\nMany thanks to Alan for testing and for the reproducer.",
"id": "GHSA-ccmh-pfgg-525g",
"modified": "2025-06-04T15:30:28Z",
"published": "2025-05-20T18:30:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-37953"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/31ff70ad39485698cf779f2078132d80b57f6c07"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3769478610135e82b262640252d90f6efb05be71"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/98cd7ed92753090a714f0802d4434314526fe61d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/99ff8a20fd61315bf9ae627440a5ff07d22ee153"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c4792b9e38d2f61b07eac72f10909fa76130314b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c928dd4f6bf0c25c72b11824a1e9ac9bd37296a0"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
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