From df4953e4e997e273501339f607b77953772e3559 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 26 Apr 2020 18:19:07 -0700 Subject: sch_sfq: validate silly quantum values syzbot managed to set up sfq so that q->scaled_quantum was zero, triggering an infinite loop in sfq_dequeue() More generally, we must only accept quantum between 1 and 2^18 - 7, meaning scaled_quantum must be in [1, 0x7FFF] range. Otherwise, we also could have a loop in sfq_dequeue() if scaled_quantum happens to be 0x8000, since slot->allot could indefinitely switch between 0 and 0x8000. Fixes: eeaeb068f139 ("sch_sfq: allow big packets and be fair") Signed-off-by: Eric Dumazet Reported-by: syzbot+0251e883fe39e7a0cb0a@syzkaller.appspotmail.com Cc: Jason A. Donenfeld Signed-off-by: David S. Miller --- net/sched/sch_sfq.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'net/sched/sch_sfq.c') diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index c787d4d46017b..5a6def5e4e6df 100644 --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -637,6 +637,15 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt) if (ctl->divisor && (!is_power_of_2(ctl->divisor) || ctl->divisor > 65536)) return -EINVAL; + + /* slot->allot is a short, make sure quantum is not too big. */ + if (ctl->quantum) { + unsigned int scaled = SFQ_ALLOT_SIZE(ctl->quantum); + + if (scaled <= 0 || scaled > SHRT_MAX) + return -EINVAL; + } + if (ctl_v1 && !red_check_params(ctl_v1->qth_min, ctl_v1->qth_max, ctl_v1->Wlog)) return -EINVAL; -- cgit 1.2.3-korg