Re: [PATCH net 04/13] net: sched: cls_u32: make sure that divisor is a power of 2

[Jamal Hadi Salim]

On 2018-09-08 9:31 p.m., Al Viro wrote:

From: Al Viro 
 > Signed-off-by: Al Viro 


Test is by hacking user space iproute2 to allow
sending a divisor > 255

Tested-by: Jamal Hadi Salim 
Acked-by: Jamal Hadi Salim 

cheers,
jamal

[PATCH net 04/13] net: sched: cls_u32: make sure that divisor is a power of 2

[Al Viro]

From: Al Viro 

Signed-off-by: Al Viro 
---
 net/sched/cls_u32.c | 6 +-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index 72459b09d910..d9923d474b65 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;
}
-- 
2.11.0