[NET_SCHED]: cls_flow: fix key mask validity check

Since we're using fls(), we need to check whether the value is
non-zero first.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c
index 8d7698621f0a..eeb223cf14cf 100644
--- a/net/sched/cls_flow.c
+++ b/net/sched/cls_flow.c
@@ -402,12 +402,13 @@ static int flow_change(struct tcf_proto *tp, unsigned long base,
 
         if (tb[TCA_FLOW_KEYS]) {
                 keymask = nla_get_u32(tb[TCA_FLOW_KEYS]);
-                if (fls(keymask) - 1 > FLOW_KEY_MAX)
-                        return -EOPNOTSUPP;
 
                 nkeys = hweight32(keymask);
                 if (nkeys == 0)
                         return -EINVAL;
+
+                if (fls(keymask) - 1 > FLOW_KEY_MAX)
+                        return -EOPNOTSUPP;
         }
 
         err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &flow_ext_map);