[PATCH next] ice: Fix signedness bug in ice_init_interrupt_scheme()

[PATCH next] ice: Fix signedness bug in ice_init_interrupt_scheme()

[Dan Carpenter]

If pci_alloc_irq_vectors() can't allocate the minimum number of vectors
then it returns -ENOSPC so there is no need to check for that in the
caller.  In fact, because pf->msix.min is an unsigned int, it means that
any negative error codes are type promoted to high positive values and
treated as success.  So here the "return -ENOMEM;" is unreachable code.
Check for negatives instead.

Fixes: 79d97b8cf9a8 ("ice: remove splitting MSI-X between features")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 drivers/net/ethernet/intel/ice/ice_irq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_irq.c b/drivers/net/ethernet/intel/ice/ice_irq.c
index cbae3d81f0f1..b1fdad154203 100644
--- a/drivers/net/ethernet/intel/ice/ice_irq.c
+++ b/drivers/net/ethernet/intel/ice/ice_irq.c
@@ -149,7 +149,7 @@ int ice_init_interrupt_scheme(struct ice_pf *pf)
 
 	vectors = pci_alloc_irq_vectors(pf->pdev, pf->msix.min, vectors,
 					PCI_IRQ_MSIX);
-	if (vectors < pf->msix.min)
+	if (vectors < 0)
 		return -ENOMEM;
 
 	ice_init_irq_tracker(pf, pf->msix.max, vectors);
-- 
2.47.2

Re: [PATCH next] ice: Fix signedness bug in ice_init_interrupt_scheme()

[Alexander Lobakin]

From: Dan Carpenter <dan.carpenter@linaro.org>
Date: Wed, 12 Feb 2025 18:27:09 +0300

> [PATCH next] ice: Fix signedness bug in ice_init_interrupt_scheme()

I believe it should be "PATCH net" with

> If pci_alloc_irq_vectors() can't allocate the minimum number of vectors
> then it returns -ENOSPC so there is no need to check for that in the
> caller.  In fact, because pf->msix.min is an unsigned int, it means that
> any negative error codes are type promoted to high positive values and
> treated as success.  So here the "return -ENOMEM;" is unreachable code.
> Check for negatives instead.
> 
> Fixes: 79d97b8cf9a8 ("ice: remove splitting MSI-X between features")

a 'Stable:' tag here.

> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> ---
>  drivers/net/ethernet/intel/ice/ice_irq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_irq.c b/drivers/net/ethernet/intel/ice/ice_irq.c
> index cbae3d81f0f1..b1fdad154203 100644
> --- a/drivers/net/ethernet/intel/ice/ice_irq.c
> +++ b/drivers/net/ethernet/intel/ice/ice_irq.c
> @@ -149,7 +149,7 @@ int ice_init_interrupt_scheme(struct ice_pf *pf)
>  
>  	vectors = pci_alloc_irq_vectors(pf->pdev, pf->msix.min, vectors,
>  					PCI_IRQ_MSIX);
> -	if (vectors < pf->msix.min)
> +	if (vectors < 0)
>  		return -ENOMEM;

This pattern most likely repeats in other Intel drivers >_<

BTW it's a bit weird that we return -ENOMEM here, although we have a
precise errno in case of error. Shouldn't we do `return vectors` here?

(but this is more of an improvement, not a fix, so out of this patch's
 scope)

>  
>  	ice_init_irq_tracker(pf, pf->msix.max, vectors);

Thanks,
Olek

Re: [PATCH next] ice: Fix signedness bug in ice_init_interrupt_scheme()

[Jakub Kicinski]

On Wed, 12 Feb 2025 17:46:54 +0100 Alexander Lobakin wrote:
> > [PATCH next] ice: Fix signedness bug in ice_init_interrupt_scheme()  
> 
> I believe it should be "PATCH net" with
> 
> > If pci_alloc_irq_vectors() can't allocate the minimum number of vectors
> > then it returns -ENOSPC so there is no need to check for that in the
> > caller.  In fact, because pf->msix.min is an unsigned int, it means that
> > any negative error codes are type promoted to high positive values and
> > treated as success.  So here the "return -ENOMEM;" is unreachable code.
> > Check for negatives instead.
> > 
> > Fixes: 79d97b8cf9a8 ("ice: remove splitting MSI-X between features")  
> 
> a 'Stable:' tag here.

Bug only exists in net-next if it comes from commit under Fixes.
So I think the patch is good as is.

Re: [PATCH next] ice: Fix signedness bug in ice_init_interrupt_scheme()

[Dan Carpenter]

On Wed, Feb 12, 2025 at 05:59:01PM -0800, Jakub Kicinski wrote:
> On Wed, 12 Feb 2025 17:46:54 +0100 Alexander Lobakin wrote:
> > > [PATCH next] ice: Fix signedness bug in ice_init_interrupt_scheme()  
> > 
> > I believe it should be "PATCH net" with
> > 
> > > If pci_alloc_irq_vectors() can't allocate the minimum number of vectors
> > > then it returns -ENOSPC so there is no need to check for that in the
> > > caller.  In fact, because pf->msix.min is an unsigned int, it means that
> > > any negative error codes are type promoted to high positive values and
> > > treated as success.  So here the "return -ENOMEM;" is unreachable code.
> > > Check for negatives instead.
> > > 
> > > Fixes: 79d97b8cf9a8 ("ice: remove splitting MSI-X between features")  
> > 
> > a 'Stable:' tag here.
> 
> Bug only exists in net-next if it comes from commit under Fixes.
> So I think the patch is good as is.

I want to resen this.  My scripts should have put a net-next in the
subject and I think that changing:

-		return -ENOMEM;
+		return vectors;

actually does fall within the scope of the patch so I want to change
that as well.  There is no point in really breaking that into a separate
patch from a practical perspective.

regards,
dan carpenter

Re: [PATCH next] ice: Fix signedness bug in ice_init_interrupt_scheme()

[Michal Swiatkowski]

On Thu, Feb 13, 2025 at 08:26:09AM +0300, Dan Carpenter wrote:
> On Wed, Feb 12, 2025 at 05:59:01PM -0800, Jakub Kicinski wrote:
> > On Wed, 12 Feb 2025 17:46:54 +0100 Alexander Lobakin wrote:
> > > > [PATCH next] ice: Fix signedness bug in ice_init_interrupt_scheme()  
> > > 
> > > I believe it should be "PATCH net" with
> > > 
> > > > If pci_alloc_irq_vectors() can't allocate the minimum number of vectors
> > > > then it returns -ENOSPC so there is no need to check for that in the
> > > > caller.  In fact, because pf->msix.min is an unsigned int, it means that
> > > > any negative error codes are type promoted to high positive values and
> > > > treated as success.  So here the "return -ENOMEM;" is unreachable code.
> > > > Check for negatives instead.
> > > > 
> > > > Fixes: 79d97b8cf9a8 ("ice: remove splitting MSI-X between features")  
> > > 
> > > a 'Stable:' tag here.
> > 
> > Bug only exists in net-next if it comes from commit under Fixes.
> > So I think the patch is good as is.
> 
> I want to resen this.  My scripts should have put a net-next in the
> subject and I think that changing:
> 
> -		return -ENOMEM;
> +		return vectors;
> 
> actually does fall within the scope of the patch so I want to change
> that as well.  There is no point in really breaking that into a separate
> patch from a practical perspective.

Thanks for fixing, I blindly followed scheme from idpf (there is the
same issue). However in ice it was done correctly before my patch.

Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>

> 
> regards,
> dan carpenter