[PATCH 5.10 120/406] net/sched: sch_hfsc: Ensure inner classes have fsc curve

Greg Kroah-Hartman
2023-09-17T19:24:42Z

From: Budimir Markovic <markovicbudimir@gmail.com>

[ Upstream commit b3d26c5702c7d6c45456326e56d2ccf3f103e60f ]

HFSC assumes that inner classes have an fsc curve, but it is currently
possible for classes without an fsc curve to become parents. This leads
to bugs including a use-after-free.

Don't allow non-root classes without HFSC_FSC to become parents.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Budimir Markovic <markovicbudimir@gmail.com>
Signed-off-by: Budimir Markovic <markovicbudimir@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://lore.kernel.org/r/20230824084905.422-1-markovicbudimir@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sched/sch_hfsc.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index cdc43a06aa9bc..6076294a632c5 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -1012,6 +1012,10 @@ hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
if (parent == NULL)
return -ENOENT;
}
+ if (!(parent->cl_flags & HFSC_FSC) && parent != &q->root) {
+ NL_SET_ERR_MSG(extack, "Invalid parent - parent class must have FSC");
+ return -EINVAL;
+ }

if (classid == 0 || TC_H_MAJ(classid ^ sch->handle) != 0)
return -EINVAL;
--
2.40.1