[PATCH net] mlxsw: spectrum_router: Fix rollback in tunnel next hop init

[PATCH net] mlxsw: spectrum_router: Fix rollback in tunnel next hop init

[Ido Schimmel]

From: Petr Machata <petrm@nvidia.com>

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>
---
 .../net/ethernet/mellanox/mlxsw/spectrum_router.c  | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 0b103fc68a1a..63652460c40d 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -4323,6 +4323,8 @@ 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;
 }
@@ -6498,6 +6500,7 @@ 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;
@@ -6513,7 +6516,16 @@ 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,
-- 
2.36.1

Re: [PATCH net] mlxsw: spectrum_router: Fix rollback in tunnel next hop init

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by Paolo Abeni <pabeni@redhat.com>:

On Wed, 29 Jun 2022 10:02:05 +0300 you wrote:
> From: Petr Machata <petrm@nvidia.com>
> 
> 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.
> 
> [...]

Here is the summary with links:
  - [net] mlxsw: spectrum_router: Fix rollback in tunnel next hop init
    https://git.kernel.org/netdev/net/c/665030fd0c1e

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html