linux-kernel - Re: [PATCH] xen/pirq: fix error path cleanup when binding MSIs

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Date:   Wed, 28 Feb 2018 09:22:49 +0000
From:   "Shah, Amit" <aams@...zon.de>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "roger.pau@...rix.com" <roger.pau@...rix.com>
CC:     "boris.ostrovsky@...cle.com" <boris.ostrovsky@...cle.com>,
        "jgross@...e.com" <jgross@...e.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>
Subject: Re: [PATCH] xen/pirq: fix error path cleanup when binding MSIs


On Mi, 2018-02-28 at 09:19 +0000, Roger Pau Monne wrote:
> Current cleanup in the error path of xen_bind_pirq_msi_to_irq is
> wrong. First of all there's an off-by-one in the cleanup loop, which
> can lead to unbinding wrong IRQs.
> 
> Secondly IRQs not bound won't be freed, thus leaking IRQ numbers.
> 
> Note that there's no need to differentiate between bound and unbound
> IRQs when freeing them, __unbind_from_irq will deal with both of them
> correctly.
> 
> Fixes: 4892c9b4ada9f9 ("xen: add support for MSI message groups")
> Reported-by: Hooman Mirhadi <mirhadih@...zon.com>
> Signed-off-by: Roger Pau Monné <roger.pau@...rix.com>
> ---
> Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> Cc: Juergen Gross <jgross@...e.com>
> Cc: Amit Shah <aams@...zon.com>
> CC: stable@...r.kernel.org
> Cc: xen-devel@...ts.xenproject.org
> ---
>  drivers/xen/events/events_base.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/xen/events/events_base.c
> b/drivers/xen/events/events_base.c
> index b241bfa529ce..159faf1269fb 100644
> --- a/drivers/xen/events/events_base.c
> +++ b/drivers/xen/events/events_base.c
> @@ -763,8 +763,8 @@ int xen_bind_pirq_msi_to_irq(struct pci_dev *dev,
> struct msi_desc *msidesc,
>  	mutex_unlock(&irq_mapping_update_lock);
>  	return irq;
>  error_irq:
> -	for (; i >= 0; i--)
> -		__unbind_from_irq(irq + i);
> +	while (nvec--)
> +		__unbind_from_irq(irq + nvec);
>  	mutex_unlock(&irq_mapping_update_lock);
>  	return ret;
>  }

Reviewed-by: Amit Shah <aams@...zon.com>


				Amit

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