CVE-2025-38000
sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue()
We use these services and cookies to improve your user experience. You may opt out if you wish, however, this may limit some features on this site.
Please see our statement on Data Privacy.
sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue()
In the Linux kernel, the following vulnerability has been resolved: sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue() When enqueuing the first packet to an HFSC class, hfsc_enqueue() calls the child qdisc's peek() operation before incrementing sch->q.qlen and sch->qstats.backlog. If the child qdisc uses qdisc_peek_dequeued(), this may trigger an immediate dequeue and potential packet drop. In such cases, qdisc_tree_reduce_backlog() is called, but the HFSC qdisc's qlen and backlog have not yet been updated, leading to inconsistent queue accounting. This can leave an empty HFSC class in the active list, causing further consequences like use-after-free. This patch fixes the bug by moving the increment of sch->q.qlen and sch->qstats.backlog before the call to the child qdisc's peek() operation. This ensures that queue length and backlog are always accurate when packet drops or dequeues are triggered during the peek.
Reserved 2025-04-16 | Published 2025-06-06 | Updated 2025-06-06 | Assigner Linuxgit.kernel.org/...c/1034e3310752e8675e313f7271b348914008719a
git.kernel.org/...c/f9f593e34d2fb67644372c8f7b033bdc622ad228
git.kernel.org/...c/89c301e929a0db14ebd94b4d97764ce1d6981653
git.kernel.org/...c/f1dde3eb17dc1b8bd07aed00004b1e05fc87a3d4
git.kernel.org/...c/93c276942e75de0e5bc91576300d292e968f5a02
git.kernel.org/...c/49b21795b8e5654a7df3d910a12e1060da4c04cf
git.kernel.org/...c/3f3a22eebbc32b4fa8ce9c1d5f9db214b45b9335
git.kernel.org/...c/3f981138109f63232a5fb7165938d4c945cc1b9d
Support options
