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authorEric Dumazet <edumazet@google.com>2021-09-04 01:03:43 +0300
committerDavid S. Miller <davem@davemloft.net>2021-09-04 12:49:46 +0300
commitc7c5e6ff533fe1f9afef7d2fa46678987a1335a7 (patch)
tree73d9af6b6cc1fc846633747ce81c900a46e27960 /net
parent10905b4a68cc58863e04d5ea5864323cb9341f9b (diff)
downloadlinux-c7c5e6ff533fe1f9afef7d2fa46678987a1335a7.tar.xz
fq_codel: reject silly quantum parameters
syzbot found that forcing a big quantum attribute would crash hosts fast, essentially using this: tc qd replace dev eth0 root fq_codel quantum 4294967295 This is because fq_codel_dequeue() would have to loop ~2^31 times in : if (flow->deficit <= 0) { flow->deficit += q->quantum; list_move_tail(&flow->flowchain, &q->old_flows); goto begin; } SFQ max quantum is 2^19 (half a megabyte) Lets adopt a max quantum of one megabyte for FQ_CODEL. Fixes: 4b549a2ef4be ("fq_codel: Fair Queue Codel AQM") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/sched/sch_fq_codel.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index c4afdd026f51..bb0cd6d3d2c2 100644
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -369,6 +369,7 @@ static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
{
struct fq_codel_sched_data *q = qdisc_priv(sch);
struct nlattr *tb[TCA_FQ_CODEL_MAX + 1];
+ u32 quantum = 0;
int err;
if (!opt)
@@ -386,6 +387,13 @@ static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
q->flows_cnt > 65536)
return -EINVAL;
}
+ if (tb[TCA_FQ_CODEL_QUANTUM]) {
+ quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
+ if (quantum > FQ_CODEL_QUANTUM_MAX) {
+ NL_SET_ERR_MSG(extack, "Invalid quantum");
+ return -EINVAL;
+ }
+ }
sch_tree_lock(sch);
if (tb[TCA_FQ_CODEL_TARGET]) {
@@ -412,8 +420,8 @@ static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
if (tb[TCA_FQ_CODEL_ECN])
q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
- if (tb[TCA_FQ_CODEL_QUANTUM])
- q->quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
+ if (quantum)
+ q->quantum = quantum;
if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
q->drop_batch_size = max(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));