[PATCH 4.16 017/161] net: dsa: bcm_sf2: Fix IPv6 rule half deletion

[Greg Kroah-Hartman]

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Florian Fainelli <f.fainelli@xxxxxxxxx>

[ Upstream commit 1942adf64214df370350aa46954ba27654456f68 ]

It was possible to delete only one half of an IPv6, which would leave
the second half still programmed and possibly in use. Instead of
checking for the unused bitmap, we need to check the unique bitmap, and
refuse any deletion that does not match that criteria. We also need to
move that check from bcm_sf2_cfp_rule_del_one() into its caller:
bcm_sf2_cfp_rule_del() otherwise we would not be able to delete second
halves anymore that would not pass the first test.

Fixes: ba0696c22e7c ("net: dsa: bcm_sf2: Add support for IPv6 CFP rules")
Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/dsa/bcm_sf2_cfp.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/drivers/net/dsa/bcm_sf2_cfp.c
+++ b/drivers/net/dsa/bcm_sf2_cfp.c
@@ -790,10 +790,6 @@ static int bcm_sf2_cfp_rule_del_one(stru
 	int ret;
 	u32 reg;
 
-	/* Refuse deletion of unused rules, and the default reserved rule */
-	if (!test_bit(loc, priv->cfp.used) || loc == 0)
-		return -EINVAL;
-
 	/* Indicate which rule we want to read */
 	bcm_sf2_cfp_rule_addr_set(priv, loc);
 
@@ -831,6 +827,13 @@ static int bcm_sf2_cfp_rule_del(struct b
 	u32 next_loc = 0;
 	int ret;
 
+	/* Refuse deleting unused rules, and those that are not unique since
+	 * that could leave IPv6 rules with one of the chained rule in the
+	 * table.
+	 */
+	if (!test_bit(loc, priv->cfp.unique) || loc == 0)
+		return -EINVAL;
+
 	ret = bcm_sf2_cfp_rule_del_one(priv, port, loc, &next_loc);
 	if (ret)
 		return ret;