3.16.83-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
commit d9e15a2733067c9328fb56d98fe8e574fa19ec31 upstream.
As diagnosed by Florian :
If TCA_FQ_QUANTUM is set to 0x80000000, fq_deueue()
can loop forever in :
if (f->credit <= 0) {
f->credit += q->quantum;
goto begin;
}
... because f->credit is either 0 or -2147483648.
Let's limit TCA_FQ_QUANTUM to no more than 1 << 20 :
This max value should limit risks of breaking user setups
while fixing this bug.
Fixes: afe4fd062416 ("pkt_sched: fq: Fair Queue packet scheduler")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Diagnosed-by: Florian Westphal <fw@xxxxxxxxx>
Reported-by: syzbot+dc9071cc5a85950bdfce@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.16: Drop call to NL_SET_ERR_MSG_MOD() as extack is
not supported.]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -690,7 +690,7 @@ static int fq_change(struct Qdisc *sch,
if (tb[TCA_FQ_QUANTUM]) {
u32 quantum = nla_get_u32(tb[TCA_FQ_QUANTUM]);
- if (quantum > 0)
+ if (quantum > 0 && quantum <= (1 << 20))
q->quantum = quantum;
else
err = -EINVAL;
