[PATCH 3.2 031/140] net_sched: red: Avoid illegal values

[Ben Hutchings]

3.2.100-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Nogah Frankel <nogahf@xxxxxxxxxxxx>

commit 8afa10cbe281b10371fee5a87ab266e48d71a7f9 upstream.

Check the qmin & qmax values doesn't overflow for the given Wlog value.
Check that qmin <= qmax.

Fixes: a783474591f2 ("[PKT_SCHED]: Generic RED layer")
Signed-off-by: Nogah Frankel <nogahf@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.2:
 - Drop changes in sch_sfq
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/include/net/red.h
+++ b/include/net/red.h
@@ -124,6 +124,17 @@ static inline u32 red_rmask(u8 Plog)
 	return Plog < 32 ? ((1 << Plog) - 1) : ~0UL;
 }
 
+static inline bool red_check_params(u32 qth_min, u32 qth_max, u8 Wlog)
+{
+	if (fls(qth_min) + Wlog > 32)
+		return false;
+	if (fls(qth_max) + Wlog > 32)
+		return false;
+	if (qth_max < qth_min)
+		return false;
+	return true;
+}
+
 static inline void red_set_parms(struct red_parms *p,
 				 u32 qth_min, u32 qth_max, u8 Wlog, u8 Plog,
 				 u8 Scell_log, u8 *stab)
--- a/net/sched/sch_choke.c
+++ b/net/sched/sch_choke.c
@@ -479,6 +479,9 @@ static int choke_change(struct Qdisc *sc
 
 	ctl = nla_data(tb[TCA_CHOKE_PARMS]);
 
+	if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog))
+		return -EINVAL;
+
 	if (ctl->limit > CHOKE_MAX_QUEUE)
 		return -EINVAL;
 
--- a/net/sched/sch_gred.c
+++ b/net/sched/sch_gred.c
@@ -384,6 +384,9 @@ static inline int gred_change_vq(struct
 	struct gred_sched *table = qdisc_priv(sch);
 	struct gred_sched_data *q;
 
+	if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog))
+		return -EINVAL;
+
 	if (table->tab[dp] == NULL) {
 		table->tab[dp] = kzalloc(sizeof(*q), GFP_ATOMIC);
 		if (table->tab[dp] == NULL)
--- a/net/sched/sch_red.c
+++ b/net/sched/sch_red.c
@@ -189,6 +189,8 @@ static int red_change(struct Qdisc *sch,
 		return -EINVAL;
 
 	ctl = nla_data(tb[TCA_RED_PARMS]);
+	if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog))
+		return -EINVAL;
 
 	if (ctl->limit > 0) {
 		child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit);