[PATCH] decnet: incorrect optlen size

[Roel Kluin <roel.kluin@gmail.com>]

Several functions with something like this occur:

int sock_set_foo(int optlen, ...)
{
	struct food foo;

	if (optlen < sizeof(foo))
		return -EINVAL;

	if (copy_from_user(&foo, optval, sizeof(foo)))
		return -EFAULT;
	...
}

see for instance:
grep -C5 -E -R -n "copy_from_user\(&([a-zA-Z0-9]*), optval, sizeof\(\1\)\)" net

but in __dn_setsockopt, below, the checks are slightly different.
Should maybe the changes below be apllied?

-------------->8----------------8<-----------------------
fix size checks before copy_from_user

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
---
diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
index cf0e184..45b9199 100644
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -1359,10 +1359,10 @@ static int __dn_setsockopt(struct socket *sock, int level,int optname, char __us
 	if (optlen && !optval)
 		return -EINVAL;
 
-	if (optlen > sizeof(u))
+	if (optlen < sizeof(u))
 		return -EINVAL;
 
-	if (copy_from_user(&u, optval, optlen))
+	if (copy_from_user(&u, optval, sizeof(u)))
 		return -EFAULT;
 
 	switch(optname) {