| From | Ben Hutchings <> | Date | Fri, 24 Apr 2020 00:06:30 +0100 | Subject | [PATCH 3.16 163/245] pkt_sched: fq: do not accept silly TCA_FQ_QUANTUM |
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3.16.83-rc1 review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
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@google.com> Diagnosed-by: Florian Westphal <fw@strlen.de> Reported-by: syzbot+dc9071cc5a85950bdfce@syzkaller.appspotmail.com Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.16: Drop call to NL_SET_ERR_MSG_MOD() as extack is not supported.] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- --- 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;
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