Messages in this thread Patch in this message | | | From | Wei Yang <> | Subject | [PATCH] iommu: WARN_ON when removing a device with no iommu_group associated | Date | Fri, 23 Aug 2013 09:55:11 +0800 |
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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 <weiyang@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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