linux-kernel - Re: [PATCH v2] irqchip/gicv3-its: Don't allow devices whose ID is outside range

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Date:	Tue, 1 Mar 2016 06:27:45 -0600
From:	Shanker Donthineni <shankerd@...eaurora.org>
To:	Eric Auger <eric.auger@...aro.org>,
	Marc Zyngier <marc.zyngier@....com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Vikram Sethi <vikrams@...eaurora.org>
Subject: Re: [PATCH v2] irqchip/gicv3-its: Don't allow devices whose ID is
 outside range

Hi Eric,

On 03/01/2016 03:42 AM, Eric Auger wrote:
> Hi Shanker,
> On 02/28/2016 08:22 PM, Shanker Donthineni wrote:
>> We are not checking whether the requested device identifier fits into
>> the device table memory or not. The function its_create_device()
>> assumes that enough memory has been allocated for whole DevID sparse
> space?
Sure, I will change to space.
>> (reported by ITS_TYPER.Devbits) during the ITS probe() and continues
>> to initialize ITS hardware.
>>
>> This assumption is not perfect, sometimes we reduce memory size either
>> because of its size crossing MAX_ORDER-1 or BASERn max size limit. The
>> MAPD command fails if 'Device ID' is outside of device table range.
>>
>> Add a simple validation check to avoid MAPD failures since we are
>> not handling ITS command errors. This change also helps to return an
>> error -ENOMEM instead of success to caller.
>>
>> Signed-off-by: Shanker Donthineni <shankerd@...eaurora.org>
>> ---
>> [v1]->[v2]
>>    Rebase to v4.5-rc6, edit commit text and simplify code changes
>>
>>   drivers/irqchip/irq-gic-v3-its.c | 24 ++++++++++++++++++++----
>>   1 file changed, 20 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
>> index 43dfd15..6d986ac 100644
>> --- a/drivers/irqchip/irq-gic-v3-its.c
>> +++ b/drivers/irqchip/irq-gic-v3-its.c
>> @@ -55,6 +55,16 @@ struct its_collection {
>>   };
>>   
>>   /*
>> + * The ITS_BASER structure - contains memeory information and table
> typo: memory

Thanks, I will fix in next patch.
> Reviewed-by: Eric Auger <eric.auger@...aro.org>
>
> Best Regards
>
> Eric
>> + * entry size in bytes.
>> + */
>> +struct its_baser {
>> +	void		*base;
>> +	u32		order;
>> +	u32		entry_size;
>> +};
>> +
>> +/*
>>    * The ITS structure - contains most of the infrastructure, with the
>>    * top-level MSI domain, the command queue, the collections, and the
>>    * list of devices writing to it.
>> @@ -66,14 +76,12 @@ struct its_node {
>>   	unsigned long		phys_base;
>>   	struct its_cmd_block	*cmd_base;
>>   	struct its_cmd_block	*cmd_write;
>> -	struct {
>> -		void		*base;
>> -		u32		order;
>> -	} tables[GITS_BASER_NR_REGS];
>> +	struct its_baser	tables[GITS_BASER_NR_REGS];
>>   	struct its_collection	*collections;
>>   	struct list_head	its_device_list;
>>   	u64			flags;
>>   	u32			ite_size;
>> +	struct its_baser	*device_table;
>>   };
>>   
>>   #define ITS_ITT_ALIGN		SZ_256
>> @@ -860,6 +868,7 @@ static int its_alloc_tables(const char *node_name, struct its_node *its)
>>   		 * For other tables, only allocate a single page.
>>   		 */
>>   		if (type == GITS_BASER_TYPE_DEVICE) {
>> +			its->device_table = &its->tables[i];
>>   			/*
>>   			 * 'order' was initialized earlier to the default page
>>   			 * granule of the the ITS.  We can't have an allocation
>> @@ -874,6 +883,7 @@ static int its_alloc_tables(const char *node_name, struct its_node *its)
>>   					node_name, order);
>>   			}
>>   		}
>> +		its->tables[i].entry_size = entry_size;
>>   
>>   retry_alloc_baser:
>>   		alloc_pages = (PAGE_ORDER_TO_SIZE(order) / psz);
>> @@ -1152,6 +1162,12 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
>>   	int nr_ites;
>>   	int sz;
>>   
>> +	/* Don't allow 'dev_id' that exceeds single, flat table limit */
>> +	if (its->device_table &&
>> +	    (dev_id >= (PAGE_ORDER_TO_SIZE(its->device_table->order) /
>> +	    its->device_table->entry_size)))
>> +		return NULL;
>> +
>>   	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
>>   	/*
>>   	 * At least one bit of EventID is being used, hence a minimum
>>

-- 
Shanker Donthineni
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project