sit: use __GFP_NOWARN for user controlled allocation

jira LE-1907
Rebuild_History Non-Buildable kernel-3.10.0-862.el7
commit-author WANG Cong <xiyou.wangcong@gmail.com>
commit 0ccc22f

The memory allocation size is controlled by user-space,
if it is too large just fail silently and return NULL,
not to mention there is a fallback allocation later.

	Reported-by: Andrey Konovalov <andreyknvl@google.com>
	Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
	Tested-by: Andrey Konovalov <andreyknvl@google.com>
	Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 0ccc22f)
	Signed-off-by: Jonathan Maple <jmaple@ciq.com>

Author: PlaidCat

net/ipv6/sit.c

@@ -304,7 +304,7 @@ static int ipip6_tunnel_get_prl(struct ip_tunnel *t,
 	 * we try harder to allocate.
 	 */
 	kp = (cmax <= 1 || capable(CAP_NET_ADMIN)) ?
-		kcalloc(cmax, sizeof(*kp), GFP_KERNEL) :
+		kcalloc(cmax, sizeof(*kp), GFP_KERNEL | __GFP_NOWARN) :
 		NULL;
 
 	rcu_read_lock();