[PATCH 4.19 248/321] iommu/amd: Fix NULL dereference bug in match_hid_uid

Greg Kroah-Hartman
2019-12-03T23:01:36Z

From: Aaron Ma <aaron.ma@canonical.com>

[ Upstream commit bb6bccba390c7d743c1e4427de4ef284c8cc6869 ]

Add a non-NULL check to fix potential NULL pointer dereference
Cleanup code to call function once.

Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
Fixes: 2bf9a0a12749b ('iommu/amd: Add iommu support for ACPI HID devices')
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/iommu/amd_iommu.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 1f2ed44de2438..fe18804a50083 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -139,10 +139,14 @@ static struct lock_class_key reserved_rbtree_key;
static inline int match_hid_uid(struct device *dev,
struct acpihid_map_entry *entry)
{
+ struct acpi_device *adev = ACPI_COMPANION(dev);
const char *hid, *uid;

- hid = acpi_device_hid(ACPI_COMPANION(dev));
- uid = acpi_device_uid(ACPI_COMPANION(dev));
+ if (!adev)
+ return -ENODEV;
+
+ hid = acpi_device_hid(adev);
+ uid = acpi_device_uid(adev);

if (!hid || !(*hid))
return -ENODEV;
--
2.20.1