linux-kernel - [PATCH] iommu: Sanity check on param list for iommu_get_resv

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Message-ID: <TYTP286MB35645FDEF45FDFC91D35CE1ECAC2A@TYTP286MB3564.JPNP286.PROD.OUTLOOK.COM>
Date:   Wed, 27 Sep 2023 22:25:01 +0800
From:   Dawei Li <set_pte_at@...look.com>
To:     joro@...tes.org, will@...nel.org
Cc:     robin.murphy@....com, jgg@...dia.com, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org, Dawei Li <set_pte_at@...look.com>
Subject: [PATCH] iommu: Sanity check on param list for iommu_get_resv_regions

In iommu_get_resv_regions(), param list is an argument supplied by caller,
into which callee is supposed to insert resv regions.

In other words, this 'list' argument is expected to be an empty list,
so make an explicit annotation on it.

Signed-off-by: Dawei Li <set_pte_at@...look.com>
---
 drivers/iommu/iommu.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 1ecac2b5c54f..a01c4a7a9d19 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -813,7 +813,7 @@ int iommu_get_group_resv_regions(struct iommu_group *group,
 
 	mutex_lock(&group->mutex);
 	for_each_group_device(group, device) {
-		struct list_head dev_resv_regions;
+		LIST_HEAD(dev_resv_regions);
 
 		/*
 		 * Non-API groups still expose reserved_regions in sysfs,
@@ -822,7 +822,6 @@ int iommu_get_group_resv_regions(struct iommu_group *group,
 		if (!device->dev->iommu)
 			break;
 
-		INIT_LIST_HEAD(&dev_resv_regions);
 		iommu_get_resv_regions(device->dev, &dev_resv_regions);
 		ret = iommu_insert_device_resv_regions(&dev_resv_regions, head);
 		iommu_put_resv_regions(device->dev, &dev_resv_regions);
@@ -1061,12 +1060,11 @@ static int iommu_create_device_direct_mappings(struct iommu_domain *domain,
 					       struct device *dev)
 {
 	struct iommu_resv_region *entry;
-	struct list_head mappings;
 	unsigned long pg_size;
+	LIST_HEAD(mappings);
 	int ret = 0;
 
 	pg_size = domain->pgsize_bitmap ? 1UL << __ffs(domain->pgsize_bitmap) : 0;
-	INIT_LIST_HEAD(&mappings);
 
 	if (WARN_ON_ONCE(iommu_is_dma_domain(domain) && !pg_size))
 		return -EINVAL;
@@ -2813,6 +2811,9 @@ void iommu_get_resv_regions(struct device *dev, struct list_head *list)
 {
 	const struct iommu_ops *ops = dev_iommu_ops(dev);
 
+	if (WARN_ON(!list_empty(list)))
+		return;
+
 	if (ops->get_resv_regions)
 		ops->get_resv_regions(dev, list);
 }
-- 
2.25.1