| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.4 146/165] pkt_sched: fq: do not accept silly TCA_FQ_QUANTUM | Date | Sat, 11 Jan 2020 10:51:05 +0100 |
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From: Eric Dumazet <edumazet@google.com>
[ Upstream commit d9e15a2733067c9328fb56d98fe8e574fa19ec31 ]
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/sched/sch_fq.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/net/sched/sch_fq.c +++ b/net/sched/sch_fq.c @@ -787,10 +787,12 @@ 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 + } else { + NL_SET_ERR_MSG_MOD(extack, "invalid quantum"); err = -EINVAL; + } } if (tb[TCA_FQ_INITIAL_QUANTUM])
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