FAILED: patch "[PATCH] mlxsw: spectrum_router: Fix rollback in tunnel next hop init" failed to apply to 4.19-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 665030fd0c1ed9f505932e6e73e7a2c788787a0a Mon Sep 17 00:00:00 2001
From: Petr Machata <petrm@nvidia.com>
Date: Wed, 29 Jun 2022 10:02:05 +0300
Subject: [PATCH] mlxsw: spectrum_router: Fix rollback in tunnel next hop init

In mlxsw_sp_nexthop6_init(), a next hop is always added to the router
linked list, and mlxsw_sp_nexthop_type_init() is invoked afterwards. When
that function results in an error, the next hop will not have been removed
from the linked list. As the error is propagated upwards and the caller
frees the next hop object, the linked list ends up holding an invalid
object.

A similar issue comes up with mlxsw_sp_nexthop4_init(), where rollback
block does exist, however does not include the linked list removal.

Both IPv6 and IPv4 next hops have a similar issue with next-hop counter
rollbacks. As these were introduced in the same patchset as the next hop
linked list, include the cleanup in this patch.

Fixes: dbe4598c1e92 ("mlxsw: spectrum_router: Keep nexthops in a linked list")
Fixes: a5390278a5eb ("mlxsw: spectrum: Add support for setting counters on nexthops")
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Amit Cohen <amcohen@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/20220629070205.803952-1-idosch@nvidia.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 9dbb573d53ea..0d8a0068e4ca 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -4415,6 +4415,8 @@ static int mlxsw_sp_nexthop4_init(struct mlxsw_sp *mlxsw_sp,
 	return 0;
 
 err_nexthop_neigh_init:
+	list_del(&nh->router_list_node);
+	mlxsw_sp_nexthop_counter_free(mlxsw_sp, nh);
 	mlxsw_sp_nexthop_remove(mlxsw_sp, nh);
 	return err;
 }
@@ -6740,6 +6742,7 @@ static int mlxsw_sp_nexthop6_init(struct mlxsw_sp *mlxsw_sp,
 				  const struct fib6_info *rt)
 {
 	struct net_device *dev = rt->fib6_nh->fib_nh_dev;
+	int err;
 
 	nh->nhgi = nh_grp->nhgi;
 	nh->nh_weight = rt->fib6_nh->fib_nh_weight;
@@ -6755,7 +6758,16 @@ static int mlxsw_sp_nexthop6_init(struct mlxsw_sp *mlxsw_sp,
 		return 0;
 	nh->ifindex = dev->ifindex;
 
-	return mlxsw_sp_nexthop_type_init(mlxsw_sp, nh, dev);
+	err = mlxsw_sp_nexthop_type_init(mlxsw_sp, nh, dev);
+	if (err)
+		goto err_nexthop_type_init;
+
+	return 0;
+
+err_nexthop_type_init:
+	list_del(&nh->router_list_node);
+	mlxsw_sp_nexthop_counter_free(mlxsw_sp, nh);
+	return err;
 }
 
 static void mlxsw_sp_nexthop6_fini(struct mlxsw_sp *mlxsw_sp,