CVE-2025-21703
netem: Update sch->q.qlen before qdisc_tree_reduce_backlog()
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Description
In the Linux kernel, the following vulnerability has been resolved: netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() qdisc_tree_reduce_backlog() notifies parent qdisc only if child qdisc becomes empty, therefore we need to reduce the backlog of the child qdisc before calling it. Otherwise it would miss the opportunity to call cops->qlen_notify(), in the case of DRR, it resulted in UAF since DRR uses ->qlen_notify() to maintain its active list.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
Patch and advisory references
- https://git.kernel.org/stable/c/1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5
- https://git.kernel.org/stable/c/6312555249082d6d8cc5321ff725df05482d8b83
- https://git.kernel.org/stable/c/638ba5089324796c2ee49af10427459c2de35f71
- https://git.kernel.org/stable/c/7b79ca9a1de6a428d486ff52fb3d602321c08f55
- https://git.kernel.org/stable/c/7f31d74fcc556a9166b1bb20515542de7bb939d1
References (11)
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