NetSight
IP …
high7.8

CVE-2025-37890

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…

Impact

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 products

VendorProductAffected versions
LinuxLinux Kernel
from 5.0.1 before 5.4.294
from 5.5 before 5.10.238
from 5.11 before 5.15.182
from 5.16 before 6.1.138
from 6.2 before 6.6.90
from 6.7 before 6.12.28
DebianDebian Linux
Version 11.0

Weakness classification

CWE-416

References