ipv4: fix ip header ident selection in __ip_make_skb()

Christian Casteyde reported a kmemcheck 32-bit read from uninitialized
memory in __ip_select_ident().

It turns out that __ip_make_skb() called ip_select_ident() before
properly initializing iph->daddr.

This is a bug uncovered by commit 1d861aa4b3fb (inet: Minimize use of
cached route inetpeer.)

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=46131

Reported-by: Christian Casteyde <casteyde.christian@free.fr>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 147ccc3e93db..c196d749daf2 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1338,10 +1338,10 @@ struct sk_buff *__ip_make_skb(struct sock *sk,
         iph->ihl = 5;
         iph->tos = inet->tos;
         iph->frag_off = df;
-        ip_select_ident(iph, &rt->dst, sk);
         iph->ttl = ttl;
         iph->protocol = sk->sk_protocol;
         ip_copy_addrs(iph, fl4);
+        ip_select_ident(iph, &rt->dst, sk);
 
         if (opt) {
                 iph->ihl += opt->optlen>>2;