[PATCH 1/2 net-next] net/mlx5e: TC: Fix IS_ERR() vs NULL checks

[PATCH 1/2 net-next] net/mlx5e: TC: Fix IS_ERR() vs NULL checks

[Dan Carpenter]

The mlx5_tc_ct_init() function doesn't return error pointers it returns
NULL.  Also we need to set the error codes on this path.

Fixes: aedd133d17bc ("net/mlx5e: Support CT offload for tc nic flows")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index 104b1c339de0..438fbcf478d1 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -5224,8 +5224,10 @@ int mlx5e_tc_nic_init(struct mlx5e_priv *priv)
 
 	tc->ct = mlx5_tc_ct_init(priv, tc->chains, &priv->fs.tc.mod_hdr,
 				 MLX5_FLOW_NAMESPACE_KERNEL);
-	if (IS_ERR(tc->ct))
+	if (!tc->ct) {
+		err = -ENOMEM;
 		goto err_ct;
+	}
 
 	tc->netdevice_nb.notifier_call = mlx5e_tc_netdev_event;
 	err = register_netdevice_notifier_dev_net(priv->netdev,
@@ -5300,8 +5300,10 @@ int mlx5e_tc_esw_init(struct rhashtable *tc_ht)
 					       esw_chains(esw),
 					       &esw->offloads.mod_hdr,
 					       MLX5_FLOW_NAMESPACE_FDB);
-	if (IS_ERR(uplink_priv->ct_priv))
+	if (!uplink_priv->ct_priv) {
+		err = -ENOMEM;
 		goto err_ct;
+	}
 
 	mapping = mapping_create(sizeof(struct tunnel_match_key),
 				 TUNNEL_INFO_BITS_MASK, true);
-- 
2.28.0

[PATCH 2/2 net-next] net/mlx5e: TC: Fix potential Oops in mlx5e_tc_unoffload_from_slow_path()

[Dan Carpenter]

If "slow_attr" is NULL then this function will Oops.

Fixes: c620b772152b ("net/mlx5: Refactor tc flow attributes structure")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index 438fbcf478d1..854153d02778 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -1238,8 +1238,10 @@ mlx5e_tc_unoffload_from_slow_path(struct mlx5_eswitch *esw,
 	struct mlx5_flow_attr *slow_attr;
 
 	slow_attr = mlx5_alloc_flow_attr(MLX5_FLOW_NAMESPACE_FDB);
-	if (!slow_attr)
+	if (!slow_attr) {
 		mlx5_core_warn(flow->priv->mdev, "Unable to unoffload slow path rule\n");
+		return;
+	}
 
 	memcpy(slow_attr, flow->attr, ESW_FLOW_ATTR_SZ);
 	slow_attr->action = MLX5_FLOW_CONTEXT_ACTION_FWD_DEST;
-- 
2.28.0

Re: [PATCH 1/2 net-next] net/mlx5e: TC: Fix IS_ERR() vs NULL checks

[Ariel Levkovich]

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Re: [PATCH 1/2 net-next] net/mlx5e: TC: Fix IS_ERR() vs NULL checks

[Dan Carpenter]

On Mon, Sep 28, 2020 at 06:31:04PM +0000, Ariel Levkovich wrote:
> On Sep 28, 2020, at 13:42, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > 
> > The mlx5_tc_ct_init() function doesn't return error pointers it returns
> > NULL.  Also we need to set the error codes on this path.
> > 
> > Fixes: aedd133d17bc ("net/mlx5e: Support CT offload for tc nic flows")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > ---
> > drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 8 ++++++--
> > 1 file changed, 6 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> > index 104b1c339de0..438fbcf478d1 100644
> > --- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> > @@ -5224,8 +5224,10 @@ int mlx5e_tc_nic_init(struct mlx5e_priv *priv)
> > 
> >    tc->ct = mlx5_tc_ct_init(priv, tc->chains, &priv->fs.tc.mod_hdr,
> >                 MLX5_FLOW_NAMESPACE_KERNEL);
> > -    if (IS_ERR(tc->ct))
> > +    if (!tc->ct) {
> > +        err = -ENOMEM;
> >        goto err_ct;
> > +    }
> 
> Hi Dan,
> That was implement like that on purpose. If mlx5_tc_init_ct returns
> NULL it means the device doesn’t support CT offload which can happen
> with older devices or old FW on the devices.
> However, in this case we want to continue with the rest of the Tc
> initialization because we can still support other TC offloads. No
> need to fail the entire TC init in this case. Only if mlx5_tc_init_ct
> return err_ptr that means the tc init failed not because of lack of
> support but due to a real error and only then we want to fail the rest
> of the tc init.
> 
> Your change will break compatibility for devices/FW versions that
> don’t have CT offload support.
> 

I should have looked at this more closely.  It seems the bug is in
mlx5_tc_ct_init().

drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c
  1897  struct mlx5_tc_ct_priv *
  1898  mlx5_tc_ct_init(struct mlx5e_priv *priv, struct mlx5_fs_chains *chains,
  1899                  struct mod_hdr_tbl *mod_hdr,
  1900                  enum mlx5_flow_namespace_type ns_type)
  1901  {
  1902          struct mlx5_tc_ct_priv *ct_priv;
  1903          struct mlx5_core_dev *dev;
  1904          const char *msg;
  1905          int err;
  1906  
  1907          dev = priv->mdev;
  1908          err = mlx5_tc_ct_init_check_support(priv, ns_type, &msg);
  1909          if (err) {
  1910                  mlx5_core_warn(dev,
  1911                                 "tc ct offload not supported, %s\n",
  1912                                 msg);
  1913                  goto err_support;

This should probably return NULL and it does.

  1914          }
  1915  
  1916          ct_priv = kzalloc(sizeof(*ct_priv), GFP_KERNEL);
  1917          if (!ct_priv)
  1918                  goto err_alloc;

This should probably return an ERR_PTR(-ENOMEM) but it instead returns
NULL.

  1919  
  1920          ct_priv->zone_mapping = mapping_create(sizeof(u16), 0, true);
  1921          if (IS_ERR(ct_priv->zone_mapping)) {
  1922                  err = PTR_ERR(ct_priv->zone_mapping);
  1923                  goto err_mapping_zone;
                        ^^^^^^^^^^^^^^^^^^^^^^
This sets "err" but it still returns NULL.

Then in the caller if the mlx5_tc_ct_init() call returns an error
pointer, it should set the error code.  (NULL is a special case of
success etc).

Can you fix this and give me a reported-by tag?  I think my new analysis
is correct...

regards,
dan carpenter

Re: [PATCH 1/2 net-next] net/mlx5e: TC: Fix IS_ERR() vs NULL checks

[Dan Carpenter]

On Mon, Sep 28, 2020 at 06:31:04PM +0000, Ariel Levkovich wrote:
> On Sep 28, 2020, at 13:42, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > 
> > The mlx5_tc_ct_init() function doesn't return error pointers it returns
> > NULL.  Also we need to set the error codes on this path.
> > 
> > Fixes: aedd133d17bc ("net/mlx5e: Support CT offload for tc nic flows")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > ---
> > drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 8 ++++++--
> > 1 file changed, 6 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> > index 104b1c339de0..438fbcf478d1 100644
> > --- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> > @@ -5224,8 +5224,10 @@ int mlx5e_tc_nic_init(struct mlx5e_priv *priv)
> > 
> >    tc->ct = mlx5_tc_ct_init(priv, tc->chains, &priv->fs.tc.mod_hdr,
> >                 MLX5_FLOW_NAMESPACE_KERNEL);
> > -    if (IS_ERR(tc->ct))
> > +    if (!tc->ct) {
> > +        err = -ENOMEM;
> >        goto err_ct;
> > +    }
> 
> Hi Dan,
> That was implement like that on purpose. If mlx5_tc_init_ct returns NULL it means the device doesn’t support CT offload which can happen with older devices or old FW on the devices.
> However, in this case we want to continue with the rest of the Tc initialization because we can still support other TC offloads. No need to fail the entire TC init in this case. Only if mlx5_tc_init_ct return err_ptr that means the tc init failed not because of lack of support but due to a real error and only then we want to fail the rest of the tc init.
> 
> Your change will break compatibility for devices/FW versions that don’t have CT offload support.
> 

When we have a function like this which is optional then returning NULL
is a special kind of success as you say.  Returning NULL should not
generate a warning message.  At the same time, if the user enables the
option and the code fails because we are low on memory then returning an
error pointer is the correct behavior.  Just because the feature is
optional does not mean we should ignore what the user told us to do.

This code never returns error pointers.  It always returns NULL/success
when an allocation fails.  That triggers the first static checker
warning from last year.  Now Smatch is complaining about a new static
checker warning:

drivers/net/ethernet/mellanox/mlx5/core/en_tc.c:4754
mlx5e_tc_esw_init() warn: missing error code here? 'IS_ERR()' failed. 'err' = '0'

  4708  int mlx5e_tc_esw_init(struct rhashtable *tc_ht)
  4709  {
  4710          const size_t sz_enc_opts = sizeof(struct tunnel_match_enc_opts);
  4711          struct mlx5_rep_uplink_priv *uplink_priv;
  4712          struct mlx5e_rep_priv *rpriv;
  4713          struct mapping_ctx *mapping;
  4714          struct mlx5_eswitch *esw;
  4715          struct mlx5e_priv *priv;
  4716          int err = 0;
  4717  
  4718          uplink_priv = container_of(tc_ht, struct mlx5_rep_uplink_priv, tc_ht);
  4719          rpriv = container_of(uplink_priv, struct mlx5e_rep_priv, uplink_priv);
  4720          priv = netdev_priv(rpriv->netdev);
  4721          esw = priv->mdev->priv.eswitch;
  4722  
  4723          uplink_priv->ct_priv = mlx5_tc_ct_init(netdev_priv(priv->netdev),
  4724                                                 esw_chains(esw),
  4725                                                 &esw->offloads.mod_hdr,
  4726                                                 MLX5_FLOW_NAMESPACE_FDB);
  4727          if (IS_ERR(uplink_priv->ct_priv))
  4728                  goto err_ct;

If mlx5_tc_ct_init() fails, which it should do if kmalloc() fails but
currently it does not, then the error should be propagated all the way
back.  So this code should preserve the error code instead of returning
success.

  4729  
  4730          mapping = mapping_create(sizeof(struct tunnel_match_key),
  4731                                   TUNNEL_INFO_BITS_MASK, true);

regards,
dan carpenter

Re: [PATCH 1/2 net-next] net/mlx5e: TC: Fix IS_ERR() vs NULL checks

[Saeed Mahameed]

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PiANCg0K

Re: [PATCH 1/2 net-next] net/mlx5e: TC: Fix IS_ERR() vs NULL checks

[Saeed Mahameed]

On Mon, 2021-02-15 at 11:30 +0300, Dan Carpenter wrote:
> On Mon, Sep 28, 2020 at 06:31:04PM +0000, Ariel Levkovich wrote:
> > On Sep 28, 2020, at 13:42, Dan Carpenter <dan.carpenter@oracle.com>
> > wrote:
> > > 
> > > The mlx5_tc_ct_init() function doesn't return error pointers it
> > > returns
> > > NULL.  Also we need to set the error codes on this path.
> > > 
> > > Fixes: aedd133d17bc ("net/mlx5e: Support CT offload for tc nic
> > > flows")
> > > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > > ---
> > > drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 8 ++++++--
> > > 1 file changed, 6 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> > > b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> > > index 104b1c339de0..438fbcf478d1 100644
> > > --- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> > > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> > > @@ -5224,8 +5224,10 @@ int mlx5e_tc_nic_init(struct mlx5e_priv
> > > *priv)
> > > 
> > >    tc->ct = mlx5_tc_ct_init(priv, tc->chains, &priv-
> > > >fs.tc.mod_hdr,
> > >                 MLX5_FLOW_NAMESPACE_KERNEL);
> > > -    if (IS_ERR(tc->ct))
> > > +    if (!tc->ct) {
> > > +        err = -ENOMEM;
> > >        goto err_ct;
> > > +    }
> > 
> > Hi Dan,
> > That was implement like that on purpose. If mlx5_tc_init_ct returns
> > NULL it means the device doesn’t support CT offload which can
> > happen with older devices or old FW on the devices.
> > However, in this case we want to continue with the rest of the Tc
> > initialization because we can still support other TC offloads. No
> > need to fail the entire TC init in this case. Only if
> > mlx5_tc_init_ct return err_ptr that means the tc init failed not
> > because of lack of support but due to a real error and only then we
> > want to fail the rest of the tc init.
> > 
> > Your change will break compatibility for devices/FW versions that
> > don’t have CT offload support.
> > 
> 
> When we have a function like this which is optional then returning
> NULL
> is a special kind of success as you say.  Returning NULL should not
> generate a warning message.  At the same time, if the user enables
> the
> option and the code fails because we are low on memory then returning
> an
> error pointer is the correct behavior.  Just because the feature is
> optional does not mean we should ignore what the user told us to do.
> 
> This code never returns error pointers.  It always returns
> NULL/success
> when an allocation fails.  That triggers the first static checker
> warning from last year.  Now Smatch is complaining about a new static
> checker warning:
> 
> drivers/net/ethernet/mellanox/mlx5/core/en_tc.c:4754
> mlx5e_tc_esw_init() warn: missing error code here? 'IS_ERR()' failed.
> 'err' = '0'
> 
>   4708  int mlx5e_tc_esw_init(struct rhashtable *tc_ht)
>   4709  {
>   4710          const size_t sz_enc_opts = sizeof(struct
> tunnel_match_enc_opts);
>   4711          struct mlx5_rep_uplink_priv *uplink_priv;
>   4712          struct mlx5e_rep_priv *rpriv;
>   4713          struct mapping_ctx *mapping;
>   4714          struct mlx5_eswitch *esw;
>   4715          struct mlx5e_priv *priv;
>   4716          int err = 0;
>   4717  
>   4718          uplink_priv = container_of(tc_ht, struct
> mlx5_rep_uplink_priv, tc_ht);
>   4719          rpriv = container_of(uplink_priv, struct
> mlx5e_rep_priv, uplink_priv);
>   4720          priv = netdev_priv(rpriv->netdev);
>   4721          esw = priv->mdev->priv.eswitch;
>   4722  
>   4723          uplink_priv->ct_priv =
> mlx5_tc_ct_init(netdev_priv(priv->netdev),
>   4724                                                
> esw_chains(esw),
>   4725                                                 &esw-
> >offloads.mod_hdr,
>   4726                                                
> MLX5_FLOW_NAMESPACE_FDB);
>   4727          if (IS_ERR(uplink_priv->ct_priv))
>   4728                  goto err_ct;
> 

The driver is designed to tolerated failure in mlx5_tc_ct_init and is
supposed to continue here and not abort with return 0..

so either return proper errno or continue initializing, the code
currently has a bug. 

Thanks Dan for pointing that out.

> If mlx5_tc_ct_init() fails, which it should do if kmalloc() fails but
> currently it does not, then the error should be propagated all the
> way
> back.  So this code should preserve the error code instead of
> returning
> success.
> 
>   4729  
>   4730          mapping = mapping_create(sizeof(struct
> tunnel_match_key),
>   4731                                   TUNNEL_INFO_BITS_MASK,
> true);
> 
> regards,
> dan carpenter
>