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>
sparknack · Oct 8, 2018 · 2f0c982 · 2f0c982
1 parent 27594ec
commit 2f0c982
Showing 1 changed file with 5 additions and 1 deletion.
diff --git 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;
 		}