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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Horatiu Vultur <horatiu.vultur@microchip.com>,
        Vladimir Oltean <vladimir.oltean@nxp.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 0370/1039] net: dsa: fix incorrect function pointer check for MRP ring roles
Date:   Mon, 24 Jan 2022 19:35:59 +0100
Message-Id: <20220124184137.738106366@linuxfoundation.org>
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From: Vladimir Oltean <vladimir.oltean@nxp.com>

[ Upstream commit ff91e1b68490b97c18c649b769618815eb945f11 ]

The cross-chip notifier boilerplate code meant to check the presence of
ds->ops->port_mrp_add_ring_role before calling it, but checked
ds->ops->port_mrp_add instead, before calling
ds->ops->port_mrp_add_ring_role.

Therefore, a driver which implements one operation but not the other
would trigger a NULL pointer dereference.

There isn't any such driver in DSA yet, so there is no reason to
backport the change. Issue found through code inspection.

Cc: Horatiu Vultur <horatiu.vultur@microchip.com>
Fixes: c595c4330da0 ("net: dsa: add MRP support")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/dsa/switch.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/dsa/switch.c b/net/dsa/switch.c
index bb155a16d4540..80816f7e1f996 100644
--- a/net/dsa/switch.c
+++ b/net/dsa/switch.c
@@ -675,7 +675,7 @@ static int
 dsa_switch_mrp_add_ring_role(struct dsa_switch *ds,
 			     struct dsa_notifier_mrp_ring_role_info *info)
 {
-	if (!ds->ops->port_mrp_add)
+	if (!ds->ops->port_mrp_add_ring_role)
 		return -EOPNOTSUPP;
 
 	if (ds->index == info->sw_index)
@@ -689,7 +689,7 @@ static int
 dsa_switch_mrp_del_ring_role(struct dsa_switch *ds,
 			     struct dsa_notifier_mrp_ring_role_info *info)
 {
-	if (!ds->ops->port_mrp_del)
+	if (!ds->ops->port_mrp_del_ring_role)
 		return -EOPNOTSUPP;
 
 	if (ds->index == info->sw_index)
-- 
2.34.1