Description
In the Linux kernel, the following vulnerability has been resolved: sch_hfsc: make hfsc_qlen_notify() idempotent hfsc_qlen_notify() is not idempotent either and not friendly to its callers, like fq_codel_dequeue(). Let's make it idempotent to ease qdisc_tree_reduce_backlog() callers' life: 1. update_vf() decreases cl->cl_nactive, so we can check whether it is non-zero before calling it. 2. eltree_remove() always removes RB node cl->el_node, but we can use RB_EMPTY_NODE() + RB_CLEAR_NODE() to make it safe.
Affected products
linux: linux kernel; debian: debian linux
References10
- git.kernel.org/stable/c/0475c85426b18eccdcb7f9fb58d8f8e9c6c58c87 Patch
- git.kernel.org/stable/c/51eb3b65544c9efd6a1026889ee5fb5aa62da3bb Patch
- git.kernel.org/stable/c/72c61ffbeeb8c50f6d4d70c65d3283aa1bac57a7 Patch
- git.kernel.org/stable/c/9030a91235ae4845ec71902c3e0cecfc9ed1f2df Patch
- git.kernel.org/stable/c/9a5fd5c2f4d4afdd5e405083ee53e0789ce76956 Patch
- git.kernel.org/stable/c/a5efc95a33bd4fcb879250852828cc58c7862970 Patch
- git.kernel.org/stable/c/c1175c4ad01dbc9c979d099861fa90a754f72059 Patch
- git.kernel.org/stable/c/d06476714d2819b550e0cc39222347e2c8941c9d Patch
- lists.debian.org/debian-lts-announce/2025/08/msg00010.html Third Party Advisory
- lists.debian.org/debian-lts-announce/2025/10/msg00007.html Third Party Advisory
Metrics
- CVSS 3.1
-
5.5
MEDIUM
Score source: NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 0% percentile: 12 · as of 7 November 2026
- CWE
- CWE-459
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