linux-kernel - [PATCH] iommu: Fix missing check for return value of iommu_group

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Date:   Wed, 14 Jun 2023 08:43:08 -0700
From:   Chenyuan Mi <cymi20@...an.edu.cn>
To:     joro@...tes.org
Cc:     will@...nel.org, robin.murphy@....com, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org, Chenyuan Mi <cymi20@...an.edu.cn>
Subject: [PATCH] iommu: Fix missing check for return value of iommu_group_get()

The iommu_group_get() function may return NULL, which may
cause null pointer deference, and most other callsites of
iommu_group_get() do Null check. Add Null check for return
value of iommu_group_get().

Found by our static analysis tool.

Signed-off-by: Chenyuan Mi <cymi20@...an.edu.cn>
---
 drivers/iommu/iommu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index f1dcfa3f1a1b..ef3483e75511 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3217,6 +3217,8 @@ EXPORT_SYMBOL_GPL(iommu_group_release_dma_owner);
 void iommu_device_release_dma_owner(struct device *dev)
 {
 	struct iommu_group *group = iommu_group_get(dev);
+	if (!group)
+		return;
 
 	mutex_lock(&group->mutex);
 	if (group->owner_cnt > 1)
@@ -3329,6 +3331,8 @@ void iommu_detach_device_pasid(struct iommu_domain *domain, struct device *dev,
 			       ioasid_t pasid)
 {
 	struct iommu_group *group = iommu_group_get(dev);
+	if (!group)
+		return;
 
 	mutex_lock(&group->mutex);
 	__iommu_remove_group_pasid(group, pasid);
-- 
2.17.1