ipv6: rt6_check should return NULL if 'from' is NULL

[ Upstream commit 49d05fe2c9d1b4a27761c9807fec39b8155bef9e ]

Paul reported that l2tp sessions were broken after the commit referenced
in the Fixes tag. Prior to this commit rt6_check returned NULL if the
rt6_info 'from' was NULL - ie., the dst_entry was disconnected from a FIB
entry. Restore that behavior.

Fixes: 93531c674315 ("net/ipv6: separate handling of FIB entries from dst based routes")
Reported-by: Paul Donohue <linux-kernel@PaulSD.com>
Tested-by: Paul Donohue <linux-kernel@PaulSD.com>
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 24f7b2cf504b2dc2ab2f6467f9a5bfd969ed3ba7..81220077d62f2280cf4fdc6e1554b6c8d8f28284 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2214,7 +2214,7 @@ static struct dst_entry *rt6_check(struct rt6_info *rt,
 {
        u32 rt_cookie = 0;
 
-       if ((from && !fib6_get_cookie_safe(from, &rt_cookie)) ||
+       if (!from || !fib6_get_cookie_safe(from, &rt_cookie) ||
            rt_cookie != cookie)
                return NULL;