5.4-stable review patch. If anyone has any objections, please let me know.
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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 92ad4115e473c..2af4adb7e84e4 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;