[PATCH net] Octeontx2-af: Fix negative array index read warning

[PATCH net] Octeontx2-af: Fix negative array index read warning

[Chandra Mohan Sundar]

The cgx_get_cgxid function may return a negative value.
Using this value directly as an array index triggers Coverity warnings.

Validate the returned value and handle the case gracefully.

Signed-off-by: Chandra Mohan Sundar <chandramohan.explore@gmail.com>
---
 drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
index 8375f18c8e07..b14de93a2481 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
@@ -3005,6 +3005,8 @@ static int cgx_print_fwdata(struct seq_file *s, int lmac_id)
 		return -EAGAIN;
 
 	cgx_id = cgx_get_cgxid(cgxd);
+	if (cgx_id < 0)
+		return -EINVAL;
 
 	if (rvu->hw->lmac_per_cgx == CGX_LMACS_USX)
 		fwdata =  &rvu->fwdata->cgx_fw_data_usx[cgx_id][lmac_id];
-- 
2.43.0

Re: [PATCH net] Octeontx2-af: Fix negative array index read warning

[Joe Damato]

On Sun, Aug 10, 2025 at 11:33:27PM +0530, Chandra Mohan Sundar wrote:
> The cgx_get_cgxid function may return a negative value.
> Using this value directly as an array index triggers Coverity warnings.
> 
> Validate the returned value and handle the case gracefully.
> 
> Signed-off-by: Chandra Mohan Sundar <chandramohan.explore@gmail.com>
> ---
>  drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
> index 8375f18c8e07..b14de93a2481 100644
> --- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
> +++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
> @@ -3005,6 +3005,8 @@ static int cgx_print_fwdata(struct seq_file *s, int lmac_id)
>  		return -EAGAIN;
>  
>  	cgx_id = cgx_get_cgxid(cgxd);
> +	if (cgx_id < 0)
> +		return -EINVAL;
>  
>  	if (rvu->hw->lmac_per_cgx == CGX_LMACS_USX)
>  		fwdata =  &rvu->fwdata->cgx_fw_data_usx[cgx_id][lmac_id];

A couple pieces of feedback for you:

1. Since this is a fixes it needs a Fixes tag and a commit SHA that it is fixing.
2. cgx_get_cgxid is called in 3 places, so your patch would probably need to
   be expanded to fix all uses?

Overall though, did you somehow trigger this issue?

It seems like all cases where cgx_get_cgxid is used it would be extremely
difficult (maybe impossible?) for cgxd to be NULL and for it to return a
negative value.

Re: [PATCH net] Octeontx2-af: Fix negative array index read warning

[Chandra Mohan Sundar]

On Mon, 11 Aug 2025 16:37:14 -0700, Joe Damato wrote:
>A couple pieces of feedback for you:

>1. Since this is a fixes it needs a Fixes tag and a commit SHA that it is fixing.

Thank you very much for your feedback.I will add the Fixes tag as suggested.

>2. cgx_get_cgxid is called in 3 places, so your patch would probably need to
>   be expanded to fix all uses?

Thanks for the suggestion.
I can add a similar check in cgxlmac_to_pf() to check if cgx_id is
negative and return an error.

>Overall though, did you somehow trigger this issue?
>
>It seems like all cases where cgx_get_cgxid is used it would be extremely
>difficult (maybe impossible?) for cgxd to be NULL and for it to return a
>negative value.

I could not reproduce a scenario where cgx_get_cgxid returns a
negative value. However, this issue was reported by the Black Duck
Coverity scan.
The fix was made to cover all possible return paths.

Please advise if you think there’s a better way to address it.

Thanks,
Chandra Mohan Sundar


On Tue, Aug 12, 2025 at 5:07 AM Joe Damato <joe@dama.to> wrote:
>
> On Sun, Aug 10, 2025 at 11:33:27PM +0530, Chandra Mohan Sundar wrote:
> > The cgx_get_cgxid function may return a negative value.
> > Using this value directly as an array index triggers Coverity warnings.
> >
> > Validate the returned value and handle the case gracefully.
> >
> > Signed-off-by: Chandra Mohan Sundar <chandramohan.explore@gmail.com>
> > ---
> >  drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
> > index 8375f18c8e07..b14de93a2481 100644
> > --- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
> > +++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
> > @@ -3005,6 +3005,8 @@ static int cgx_print_fwdata(struct seq_file *s, int lmac_id)
> >               return -EAGAIN;
> >
> >       cgx_id = cgx_get_cgxid(cgxd);
> > +     if (cgx_id < 0)
> > +             return -EINVAL;
> >
> >       if (rvu->hw->lmac_per_cgx == CGX_LMACS_USX)
> >               fwdata =  &rvu->fwdata->cgx_fw_data_usx[cgx_id][lmac_id];
>
> A couple pieces of feedback for you:
>
> 1. Since this is a fixes it needs a Fixes tag and a commit SHA that it is fixing.
> 2. cgx_get_cgxid is called in 3 places, so your patch would probably need to
>    be expanded to fix all uses?
>
> Overall though, did you somehow trigger this issue?
>
> It seems like all cases where cgx_get_cgxid is used it would be extremely
> difficult (maybe impossible?) for cgxd to be NULL and for it to return a
> negative value.