CVE-2025-37890
net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc
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Description
In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc As described in Gerrard's report [1], we have a UAF case when an hfsc class has a netem child qdisc. The crux of the issue is that hfsc is assuming that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted the class in the vttree or eltree (which is not true for the netem duplicate case). This patch checks the n_active class variable to make sure that the code won't insert the class in the vttree or eltree twice, catering for the reentrant case. [1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/
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/141d34391abbb315d68556b7c67ad97885407547
- https://git.kernel.org/stable/c/273bbcfa53541cde38b2003ad88a59b770306421
- https://git.kernel.org/stable/c/2e7093c7a8aba5d4f8809f271488e5babe75e202
- https://git.kernel.org/stable/c/6082a87af4c52f58150d40dec1716011d871ac21
- https://git.kernel.org/stable/c/8df7d37d626430035b413b97cee18396b3450bef
References (10)
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