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 products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea to < 273bbcfa53541cde38b2003ad88a59b770306421affected37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea to < e0cf8ee23e1915431f262a7b2dee0c7a7d699af0affected37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea to < e3e949a39a91d1f829a4890e7dfe9417ac72e4d0affected37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea to < 8df7d37d626430035b413b97cee18396b3450befaffected37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea to < 6082a87af4c52f58150d40dec1716011d871ac21affected37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea to < 2e7093c7a8aba5d4f8809f271488e5babe75e202affected37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea to < ac39fd4a757584d78ed062d4f6fd913f83bd98b5affected37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea to < 141d34391abbb315d68556b7c67ad97885407547affected
Linux Linux
Default version status: affected
5.0affected0 to < 5.0unaffected5.4.294 to ≤ 5.4.*unaffected5.10.238 to ≤ 5.10.*unaffected5.15.182 to ≤ 5.15.*unaffected6.1.138 to ≤ 6.1.*unaffected6.6.90 to ≤ 6.6.*unaffected6.12.28 to ≤ 6.12.*unaffected6.14.6 to ≤ 6.14.*unaffected6.15 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/273bbcfa53541cde38b2003ad88a59b770306421 ↗
- https://git.kernel.org/stable/c/e0cf8ee23e1915431f262a7b2dee0c7a7d699af0 ↗
- https://git.kernel.org/stable/c/e3e949a39a91d1f829a4890e7dfe9417ac72e4d0 ↗
- https://git.kernel.org/stable/c/8df7d37d626430035b413b97cee18396b3450bef ↗
- https://git.kernel.org/stable/c/6082a87af4c52f58150d40dec1716011d871ac21 ↗
- https://git.kernel.org/stable/c/2e7093c7a8aba5d4f8809f271488e5babe75e202 ↗
- https://git.kernel.org/stable/c/ac39fd4a757584d78ed062d4f6fd913f83bd98b5 ↗
- https://git.kernel.org/stable/c/141d34391abbb315d68556b7c67ad97885407547 ↗
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html ↗
- https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html ↗