CVEvulnerability
CVE-2026-98013
- Status
- Received
- Published
- 2026-09-25
- Last modified
- 2026-10-19
- Assigner
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Description
In the Linux kernel, the following vulnerability has been resolved:
net/sched: fq_pie: clamp quantum in change path
fq_pie_change() accepts any quantum value from userspace, including 1.
With a crafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1
makes the deficit-refill loop spin ~2^31 times under the qdisc lock
(a soft lockup / denial of service).
Add max(256U, ...) matching fq_codel_change().
Conditions to recreate the bug:
CONFIG_NET_SCH_FQ_PIE=y. Requires CAP_NET_ADMIN (namespace-local via
unshare -Urn suffices).
tc qdisc add dev dummy0 root fq_pie
tc qdisc change dev dummy0 root fq_pie quantum 1 stab data 32768 size_log 15 cell_log 0
References
- https://git.kernel.org/stable/c/215df1e953ae72a09d425ec188e054058ae23dc9 git.kernel.org
- https://git.kernel.org/stable/c/4864f58c53eb47257d55e01f47d4a9f355f7f970 git.kernel.org
- https://git.kernel.org/stable/c/6655b56e2801008566c594ef231f6c7b3f716c61 git.kernel.org
- https://git.kernel.org/stable/c/749aaebc1eb92ce2f38fd3caf68a2f99686d84ef git.kernel.org
- https://git.kernel.org/stable/c/8fd98e56c41f79278eeb67512c28d7abc175bcf4 git.kernel.org
- https://git.kernel.org/stable/c/c11e3a39807eb5a200445ae9082843ab86800415 git.kernel.org
- https://git.kernel.org/stable/c/f90fe65b977e7aa9eb302230a09eb18f8c32ceaa git.kernel.org
- https://git.kernel.org/stable/c/ff4f3a0f3abd2ded467931d7da7984a68a768e0b git.kernel.org