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])