[TCP]: Shrink syncookie_secret by 8 byte.

the first u32 copied from syncookie_secret is overwritten by the
minute-counter four lines below.  After adjusting the destination
address, the size of syncookie_secret can be reduced accordingly.

AFAICS, the only other user of syncookie_secret[] is the ipv6
syncookie support.  Because ipv6 syncookies only grab 44 bytes from
syncookie_secret[], this shouldn't affect them in any way.

With fixes from Glenn Griffin.

Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Glenn Griffin <ggriffin.kernel@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 3 insertions, 3 deletions

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 4704f27f6c0b..abc752d45cf7 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -21,7 +21,7 @@
 
 extern int sysctl_tcp_syncookies;
 
-__u32 syncookie_secret[2][16-3+SHA_DIGEST_WORDS];
+__u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
 EXPORT_SYMBOL(syncookie_secret);
 
 static __init int init_syncookies(void)
@@ -41,7 +41,7 @@ static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
 {
         __u32 *tmp = __get_cpu_var(cookie_scratch);
 
-        memcpy(tmp + 3, syncookie_secret[c], sizeof(syncookie_secret[c]));
+        memcpy(tmp + 4, syncookie_secret[c], sizeof(syncookie_secret[c]));
         tmp[0] = (__force u32)saddr;
         tmp[1] = (__force u32)daddr;
         tmp[2] = ((__force u32)sport << 16) + (__force u32)dport;
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 827c5aa7524c..3a622e7abc02 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -22,7 +22,7 @@
 #include <net/tcp.h>
 
 extern int sysctl_tcp_syncookies;
-extern __u32 syncookie_secret[2][16-3+SHA_DIGEST_WORDS];
+extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
 
 #define COOKIEBITS 24   /* Upper bits store count */
 #define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)