From: Al Viro <viro@zeniv.linux.org.uk>
Date: Mon, 8 Oct 2018 10:22:35 +0000 (-0400)
Subject: net: sched: cls_u32: make sure that divisor is a power of 2
X-Git-Tag: v4.20-rc1~14^2~132^2~9
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=2f0c982df7b146f9aa695ede91b48392ab4c3217;p=uclinux-h8%2Flinux.git

net: sched: cls_u32: make sure that divisor is a power of 2

Tested by modifying iproute2 to allow sending a divisor > 255

Tested-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index 3357331a80a2..ce55eea448a0 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -994,7 +994,11 @@ static int u32_change(struct net *net, struct sk_buff *in_skb,
 	if (tb[TCA_U32_DIVISOR]) {
 		unsigned int divisor = nla_get_u32(tb[TCA_U32_DIVISOR]);
 
-		if (--divisor > 0x100) {
+		if (!is_power_of_2(divisor)) {
+			NL_SET_ERR_MSG_MOD(extack, "Divisor is not a power of 2");
+			return -EINVAL;
+		}
+		if (divisor-- > 0x100) {
 			NL_SET_ERR_MSG_MOD(extack, "Exceeded maximum 256 hash buckets");
 			return -EINVAL;
 		}