linux-kernel - Re: [PATCH v3] irqchip/gicv3-its: Don't allow devices whose ID is outside range

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Date:	Thu, 3 Mar 2016 08:34:42 -0600
From:	Shanker Donthineni <shankerd@...eaurora.org>
To:	Marc Zyngier <marc.zyngier@....com>,
	Eric Auger <eric.auger@...aro.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:	Vikram Sethi <vikrams@...eautora.org>,
	Jason Cooper <jason@...edaemon.net>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v3] irqchip/gicv3-its: Don't allow devices whose ID is
 outside range

Hi Marc,

Do you have any comments on this patch?

On 03/01/2016 06:55 AM, 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 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.
>
> Reviewed-by: Eric Auger <eric.auger@...aro.org>
> Signed-off-by: Shanker Donthineni <shankerd@...eaurora.org>
> ---
> [v1]->[v2]
>   Rebase to v4.5-rc6, edit commit text and simplify code changes.
>
> [v2]->[v3]
>    Fix typo.
>
>  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 memory information and table
> + * 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