[PATCH] net/mlx5e: Fix freeing of unassigned pointer

[PATCH] net/mlx5e: Fix freeing of unassigned pointer

[Alex Dewar]

Commit ff7ea04ad579 ("net/mlx5e: Fix potential null pointer dereference")
added some missing null checks but the error handling in
mlx5e_alloc_flow() was left broken: the variable attr is passed to kfree
although it is never assigned to and never needs to be freed in this
function. Fix this.

Addresses-Coverity-ID: 1497536 ("Memory - illegal accesses")
Fixes: ff7ea04ad579 ("net/mlx5e: Fix potential null pointer dereference")
Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index a0c356987e1a..88298e96c4ea 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -4536,13 +4536,14 @@ mlx5e_alloc_flow(struct mlx5e_priv *priv, int attr_size,
 	struct mlx5e_tc_flow_parse_attr *parse_attr;
 	struct mlx5_flow_attr *attr;
 	struct mlx5e_tc_flow *flow;
-	int err = -ENOMEM;
 	int out_index;
 
 	flow = kzalloc(sizeof(*flow), GFP_KERNEL);
+	if (!flow)
+		return -ENOMEM;
 	parse_attr = kvzalloc(sizeof(*parse_attr), GFP_KERNEL);
-	if (!parse_attr || !flow)
-		goto err_free;
+	if (!parse_attr)
+		goto err_free_flow;
 
 	flow->flags = flow_flags;
 	flow->cookie = f->cookie;
@@ -4550,7 +4551,7 @@ mlx5e_alloc_flow(struct mlx5e_priv *priv, int attr_size,
 
 	attr = mlx5_alloc_flow_attr(get_flow_name_space(flow));
 	if (!attr)
-		goto err_free;
+		goto err_free_parse_attr;
 
 	flow->attr = attr;
 
@@ -4566,11 +4567,11 @@ mlx5e_alloc_flow(struct mlx5e_priv *priv, int attr_size,
 
 	return 0;
 
-err_free:
-	kfree(flow);
+err_free_parse_attr:
 	kvfree(parse_attr);
-	kfree(attr);
-	return err;
+err_free_flow:
+	kfree(flow);
+	return -ENOMEM;
 }
 
 static void
-- 
2.28.0

Re: [PATCH] net/mlx5e: Fix freeing of unassigned pointer

[Saeed Mahameed]

On Sat, 2020-10-03 at 12:10 +0100, Alex Dewar wrote:
> Commit ff7ea04ad579 ("net/mlx5e: Fix potential null pointer
> dereference")
> added some missing null checks but the error handling in
> mlx5e_alloc_flow() was left broken: the variable attr is passed to
> kfree
> although it is never assigned to and never needs to be freed in this
> function. Fix this.
> 
> Addresses-Coverity-ID: 1497536 ("Memory - illegal accesses")
> Fixes: ff7ea04ad579 ("net/mlx5e: Fix potential null pointer
> dereference")
> Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 17 +++++++++----
> ----
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 

Hi Alex, thanks for the patch, 
Colin submitted a one liner patch that I already picked up.

I hope you are ok with this.

Thanks,
Saeed.

Re: [PATCH] net/mlx5e: Fix freeing of unassigned pointer

[Alex Dewar]

On Tue, Oct 06, 2020 at 04:22:12PM -0700, Saeed Mahameed wrote:
> On Sat, 2020-10-03 at 12:10 +0100, Alex Dewar wrote:
> > Commit ff7ea04ad579 ("net/mlx5e: Fix potential null pointer
> > dereference")
> > added some missing null checks but the error handling in
> > mlx5e_alloc_flow() was left broken: the variable attr is passed to
> > kfree
> > although it is never assigned to and never needs to be freed in this
> > function. Fix this.
> > 
> > Addresses-Coverity-ID: 1497536 ("Memory - illegal accesses")
> > Fixes: ff7ea04ad579 ("net/mlx5e: Fix potential null pointer
> > dereference")
> > Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
> > ---
> >  drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 17 +++++++++----
> > ----
> >  1 file changed, 9 insertions(+), 8 deletions(-)
> > 
> 
> Hi Alex, thanks for the patch, 
> Colin submitted a one liner patch that I already picked up.
> 
> I hope you are ok with this.

Hi Saeed,

Sure. As long as attr is no longer being freed then that should fix the
problem.

Best,
Alex

> 
> Thanks,
> Saeed.
>