Commit f9aac066 authored by Eric Dumazet's avatar Eric Dumazet Committed by Marcelo Henrique Cerri

sch_sfq: validate silly quantum values

BugLink: https://bugs.launchpad.net/bugs/1881356

[ Upstream commit df4953e4 ]

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: eeaeb068 ("sch_sfq: allow big packets and be fair")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: syzbot+0251e883fe39e7a0cb0a@syzkaller.appspotmail.com
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarIan May <ian.may@canonical.com>
Signed-off-by: default avatarKelsey Skunberg <kelsey.skunberg@canonical.com>
parent 0c17daab
......@@ -635,6 +635,15 @@ 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;
......
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