netfilter: ipset: List timing out entries with "timeout 1" instead of zero

BugLink: https://bugs.launchpad.net/bugs/1791953

[ Upstream commit bd975e69 ]

When listing sets with timeout support, there's a probability that
just timing out entries with "0" timeout value is listed/saved.
However when restoring the saved list, the zero timeout value means
permanent elelements.

The new behaviour is that timing out entries are listed with "timeout 1"
instead of zero.

Fixes netfilter bugzilla #1258.
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

include/linux/netfilter/ipset/ip_set_timeout.h

@@ -65,8 +65,14 @@ ip_set_timeout_set(unsigned long *timeout, u32 value)
 static inline u32
 ip_set_timeout_get(unsigned long *timeout)
 {
-	return *timeout == IPSET_ELEM_PERMANENT ? 0 :
-		jiffies_to_msecs(*timeout - jiffies)/MSEC_PER_SEC;
+	u32 t;
+
+	if (*timeout == IPSET_ELEM_PERMANENT)
+		return 0;
+
+	t = jiffies_to_msecs(*timeout - jiffies)/MSEC_PER_SEC;
+	/* Zero value in userspace means no timeout */
+	return t == 0 ? 1 : t;
 }
 
 #endif	/* __KERNEL__ */