Re: [PATCH net v2] net/sched: sch_htb: limit htb_classify inner-class filter hops

On Wed, Aug 26, 2026 at 4:33 PM Victor Nogueira [off-list ref] wrote:

From: Jamal Hadi Salim <jhs@mojatatu.com>

htb_classify() follows each filter-selected inner class by switching
to cl->filter_list, but never bounds the number of hops. A filter on
an inner class can point back to itself or to another inner class that
points back, creating an infinite loop in the packet classification
path with the qdisc lock held and BH disabled — a soft lockup / panic
from a single packet.

Reviewed-by: Eric Dumazet <edumazet@google.com>

Note that a one-time warning (in the spirit of commit e82181de5ef4648
"pkt_sched: sch_htb: Warn on too many events.") could have been chosen.

Thanks.