From: Kui-Feng Lee <redacted>

Make the decision to set or clean the expires of a route based on the
RTF_EXPIRES flag, rather than the value of the "expires" argument.

The function inet6_addr_modify() is the only caller of
modify_prefix_route(), and it passes the RTF_EXPIRES flag and an expiration
value. The RTF_EXPIRES flag is turned on or off based on the value of
valid_lft. The RTF_EXPIRES flag is turned on if valid_lft is a finite value
(not infinite, not 0xffffffff). Even if valid_lft is 0, the RTF_EXPIRES
flag remains on. The expiration value being passed is equal to the
valid_lft value if the flag is on. However, if the valid_lft value is
infinite, the expiration value becomes 0 and the RTF_EXPIRES flag is turned
off. Despite this, modify_prefix_route() decides to set the expiration
value if the received expiration value is not zero. This mixing of infinite
and zero cases creates an inconsistency.

Signed-off-by: Kui-Feng Lee <redacted>
---
 net/ipv6/addrconf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 36bfa987c314..2f6cf6314646 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c

@@ -4788,7 +4788,7 @@ static int modify_prefix_route(struct inet6_ifaddr *ifp,
 	} else {
 		table = f6i->fib6_table;
 		spin_lock_bh(&table->tb6_lock);
-		if (!expires) {
+		if (!(flags & RTF_EXPIRES)) {