From d2f5fb9192b103b9aae6c3fa63ffdf04b2ecbff0 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 27 Jun 2013 13:44:26 +0200 Subject: [PATCH] nlmon: fix comparison in nlmon_is_valid_mtu This patch fixes the following warning introduced in d4c614127cb1 ("packet: nlmon: virtual netlink monitoring device for packet sockets") reported by Dan Carpenter: warning: "drivers/net/nlmon.c:31 nlmon_is_valid_mtu() warn: always true condition '(new_mtu <= ((~0 >> 1))) => (s32min-s32max <= s32max)'" Thus, we should simply remove the test against INT_MAX. Next to that we also need to explicitly cast the sizeof() case as the comparison is type promoted to unsigned long so negative values are then valid instead of invalid. While at it, this also adds a comment about Netlink and MTUs. Reported-by: Dan Carpenter Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller --- drivers/net/nlmon.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/net/nlmon.c b/drivers/net/nlmon.c index dc364be6e61e0..a0baf56f5826b 100644 --- a/drivers/net/nlmon.c +++ b/drivers/net/nlmon.c @@ -28,7 +28,11 @@ static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev) static int nlmon_is_valid_mtu(int new_mtu) { - return new_mtu >= sizeof(struct nlmsghdr) && new_mtu <= INT_MAX; + /* Note that in netlink we do not really have an upper limit. On + * default, we use NLMSG_GOODSIZE. Here at least we should make + * sure that it's at least the header size. + */ + return new_mtu >= (int) sizeof(struct nlmsghdr); } static int nlmon_change_mtu(struct net_device *dev, int new_mtu) -- 2.39.5