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Subject: Re: [PATCH] xen/pirq: fix error path cleanup when binding MSIs
To:     "Shah, Amit" <aams@amazon.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "roger.pau@citrix.com" <roger.pau@citrix.com>
Cc:     "jgross@suse.com" <jgross@suse.com>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
References: <20180228091903.99889-1-roger.pau@citrix.com>
 <1519809769.4965.26.camel@amazon.com>
From:   Boris Ostrovsky <boris.ostrovsky@oracle.com>
Message-ID: <a4e23dd6-a013-772f-3167-cf4fd92c21e7@oracle.com>
Date:   Wed, 28 Feb 2018 09:57:36 -0500
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On 02/28/2018 04:22 AM, Shah, Amit wrote:
> 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@amazon.com>
>> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
>> ---
>> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>> Cc: Juergen Gross <jgross@suse.com>
>> Cc: Amit Shah <aams@amazon.com>
>> CC: stable@vger.kernel.org
>> Cc: xen-devel@lists.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@amazon.com>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>