| Message ID | 20200427011907.160247-1-edumazet@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | [net] sch_sfq: validate silly quantum values | expand |
diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index c787d4d46017b4b41b8eb6d41f2b0a44560ff5bf..5a6def5e4e6df2e7b66c88aa877c7318270d48be 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;
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 <edumazet@google.com> Reported-by: syzbot+0251e883fe39e7a0cb0a@syzkaller.appspotmail.com Cc: Jason A. Donenfeld <Jason@zx2c4.com> --- net/sched/sch_sfq.c | 9 +++++++++ 1 file changed, 9 insertions(+)