Re: [PATCH] vdpa/mlx5: Fix erroneous null pointer checks

[Alex Dewar]

On Sun, Aug 09, 2020 at 06:03:00AM +0000, Eli Cohen wrote:
> After all this patch is not fixing it all. If we get to default of the switch statement we will free invalid pointer so removing ack-ed by me.
> 
> The previous patch by Colin King fixes it.

Good point, sounds sensible. Thanks for looking my patch over :-)

Alex

> 
> 
> -----Original Message-----
> From: Eli Cohen <eli@xxxxxxxxxxxx> 
> Sent: Sunday, August 9, 2020 8:53 AM
> To: Alex Dewar <alex.dewar90@xxxxxxxxx>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>; Jason Wang <jasowang@xxxxxxxxxx>; Parav Pandit <parav@xxxxxxxxxxxx>; virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] vdpa/mlx5: Fix erroneous null pointer checks
> 
> Acked-by: Eli Cohen <eli@xxxxxxxxxxxx>
> On Thu, Aug 06, 2020 at 08:18:39PM +0100, Alex Dewar wrote:
> > In alloc_inout() in net/mlx5_vnet.c, there are a few places where 
> > memory is allocated to *in and *out, but only the values of in and out 
> > are null-checked (i.e. there is a missing dereference). Fix this.
> > 
> > Addresses-Coverity: ("CID 1496603: (REVERSE_INULL)")
> > Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 
> > devices")
> > Signed-off-by: Alex Dewar <alex.dewar90@xxxxxxxxx>
> > ---
> >  drivers/vdpa/mlx5/net/mlx5_vnet.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c 
> > b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > index 3ec44a4f0e45..bcb6600c2839 100644
> > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > @@ -867,7 +867,7 @@ static void alloc_inout(struct mlx5_vdpa_net *ndev, int cmd, void **in, int *inl
> >  		*outlen = MLX5_ST_SZ_BYTES(qp_2rst_out);
> >  		*in = kzalloc(*inlen, GFP_KERNEL);
> >  		*out = kzalloc(*outlen, GFP_KERNEL);
> > -		if (!in || !out)
> > +		if (!*in || !*out)
> >  			goto outerr;
> >  
> >  		MLX5_SET(qp_2rst_in, *in, opcode, cmd); @@ -879,7 +879,7 @@ static 
> > void alloc_inout(struct mlx5_vdpa_net *ndev, int cmd, void **in, int *inl
> >  		*outlen = MLX5_ST_SZ_BYTES(rst2init_qp_out);
> >  		*in = kzalloc(*inlen, GFP_KERNEL);
> >  		*out = kzalloc(MLX5_ST_SZ_BYTES(rst2init_qp_out), GFP_KERNEL);
> > -		if (!in || !out)
> > +		if (!*in || !*out)
> >  			goto outerr;
> >  
> >  		MLX5_SET(rst2init_qp_in, *in, opcode, cmd); @@ -896,7 +896,7 @@ 
> > static void alloc_inout(struct mlx5_vdpa_net *ndev, int cmd, void **in, int *inl
> >  		*outlen = MLX5_ST_SZ_BYTES(init2rtr_qp_out);
> >  		*in = kzalloc(*inlen, GFP_KERNEL);
> >  		*out = kzalloc(MLX5_ST_SZ_BYTES(init2rtr_qp_out), GFP_KERNEL);
> > -		if (!in || !out)
> > +		if (!*in || !*out)
> >  			goto outerr;
> >  
> >  		MLX5_SET(init2rtr_qp_in, *in, opcode, cmd); @@ -914,7 +914,7 @@ 
> > static void alloc_inout(struct mlx5_vdpa_net *ndev, int cmd, void **in, int *inl
> >  		*outlen = MLX5_ST_SZ_BYTES(rtr2rts_qp_out);
> >  		*in = kzalloc(*inlen, GFP_KERNEL);
> >  		*out = kzalloc(MLX5_ST_SZ_BYTES(rtr2rts_qp_out), GFP_KERNEL);
> > -		if (!in || !out)
> > +		if (!*in || !*out)
> >  			goto outerr;
> >  
> >  		MLX5_SET(rtr2rts_qp_in, *in, opcode, cmd);
> > --
> > 2.28.0
> >