[NET]: Do not memcmp() over pad bytes of struct flowi.

They are not necessarily initialized to zero by the compiler,
for example when using run-time initializers of automatic
on-stack variables.

Noticed by Eric Dumazet and Patrick McHardy.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 3 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index c41ddba02e9d..925ee4dfc32c 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -566,9 +566,15 @@ static inline u32 rt_score(struct rtable *rt)
 
 static inline int compare_keys(struct flowi *fl1, struct flowi *fl2)
 {
-        return memcmp(&fl1->nl_u.ip4_u, &fl2->nl_u.ip4_u, sizeof(fl1->nl_u.ip4_u)) == 0 &&
-               fl1->oif     == fl2->oif &&
-               fl1->iif     == fl2->iif;
+        return ((fl1->nl_u.ip4_u.daddr ^ fl2->nl_u.ip4_u.daddr) |
+                (fl1->nl_u.ip4_u.saddr ^ fl2->nl_u.ip4_u.saddr) |
+#ifdef CONFIG_IP_ROUTE_FWMARK
+                (fl1->nl_u.ip4_u.fwmark ^ fl2->nl_u.ip4_u.fwmark) |
+#endif
+                (*(u16 *)&fl1->nl_u.ip4_u.tos ^
+                 *(u16 *)&fl2->nl_u.ip4_u.tos) |
+                (fl1->oif ^ fl2->oif) |
+                (fl1->iif ^ fl2->iif)) == 0;
 }
 
 #ifdef CONFIG_IP_ROUTE_MULTIPATH_CACHED