When removing a device from the system, iommu_group driver will try to
disconnect it from its group. While in some cases, one device may not
associated with any iommu_group. For example, not enough DMA address space.
In the generic bus notification, it will check dev->iommu_group before calling
iommu_group_remove_device(). While in some cases, developers may call
iommu_group_remove_device() in a different code path and without check. For
those devices with dev->iommu_group set to NULL, kernel will crash.
This patch gives a warning and return when trying to remove a device from an
iommu_group with dev->iommu_group set to NULL. This helps to indicate some bad
behavior and also guard the kernel.
Signed-off-by: Wei Yang <weiy...@linux.vnet.ibm.com>
---
drivers/iommu/iommu.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index fbe9ca7..43396f0 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -379,6 +379,9 @@ void iommu_group_remove_device(struct device *dev)
struct iommu_group *group = dev->iommu_group;
struct iommu_device *tmp_device, *device = NULL;
+ if (WARN_ON(!group))
+ return;
+
/* Pre-notify listeners that a device is being removed. */
blocking_notifier_call_chain(&group->notifier,
IOMMU_GROUP_NOTIFY_DEL_DEVICE, dev);
--
1.7.5.4
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