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

[shankerd@codeaurora.org (Shanker Donthineni)]

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
(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@codeaurora.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
+ * 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
-- 
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