2023-02-17 14:09:46

by Natalia Petrova

Subject: [PATCH] mlxsw_spectrum_router: add check for return value of 'mlxsw_sp_rif_find_by_dev'

Pointer 'rif' that contains the return value of 'mlxsw_sp_rif_find_by_dev'
is checked for NULL to avoid possible undefined behavior below caused by
dereference in 'mlxsw_sp_rif_destroy'.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: e4f3c1c17b6d ("mlxsw: spectrum_router: Implement common RIF core")
Signed-off-by: Natalia Petrova <[email protected]>
---
drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 2c4443c6b964..4f41b83d7c9e 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -8658,7 +8658,8 @@ static int mlxsw_sp_inetaddr_bridge_event(struct mlxsw_sp *mlxsw_sp,
break;
case NETDEV_DOWN:
rif = mlxsw_sp_rif_find_by_dev(mlxsw_sp, l3_dev);
- mlxsw_sp_rif_destroy(rif);
+ if (rif)
+ mlxsw_sp_rif_destroy(rif);
break;
}

--
2.34.1

2023-02-17 17:48:59

by Petr Machata

Subject: Re: [PATCH] mlxsw_spectrum_router: add check for return value of 'mlxsw_sp_rif_find_by_dev'

Natalia Petrova <[email protected]> writes:

> Pointer 'rif' that contains the return value of 'mlxsw_sp_rif_find_by_dev'
> is checked for NULL to avoid possible undefined behavior below caused by
> dereference in 'mlxsw_sp_rif_destroy'.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: e4f3c1c17b6d ("mlxsw: spectrum_router: Implement common RIF core")
> Signed-off-by: Natalia Petrova <[email protected]>
> ---
> drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> index 2c4443c6b964..4f41b83d7c9e 100644
> --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> @@ -8658,7 +8658,8 @@ static int mlxsw_sp_inetaddr_bridge_event(struct mlxsw_sp *mlxsw_sp,
> break;
> case NETDEV_DOWN:
> rif = mlxsw_sp_rif_find_by_dev(mlxsw_sp, l3_dev);
> - mlxsw_sp_rif_destroy(rif);
> + if (rif)
> + mlxsw_sp_rif_destroy(rif);
> break;
> }

I don't think this can happen. The corresponding NETDEV_UP is invoked
through address validator chain, so failures to create a RIF would be
vetoed. Furthermore the DOWN event itself is invoked by
mlxsw_sp_inetaddr_event(), where the invocation is contingent on
mlxsw_sp_rif_should_config(). That would be false if there's no RIF.