Messages in this thread Patch in this message | | | From | Joerg Roedel <> | Subject | [PATCH 2/5] x86/amd-iommu: Fix NULL pointer dereference in __detach_device() | Date | Fri, 22 Jan 2010 18:18:10 +0100 |
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In the __detach_device function the reference count for a device-domain binding may become zero. This results in the device being removed from the domain and dev_data->domain will be NULL. This is bad because this pointer is dereferenced when trying to unlock the domain->lock. This patch fixes the issue by keeping the domain in a seperate variable.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> --- arch/x86/kernel/amd_iommu.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c index c2ccbd7..4478a48 100644 --- a/arch/x86/kernel/amd_iommu.c +++ b/arch/x86/kernel/amd_iommu.c @@ -1489,11 +1489,14 @@ static void __detach_device(struct device *dev) { struct iommu_dev_data *dev_data = get_dev_data(dev); struct iommu_dev_data *alias_data; + struct protection_domain *domain; unsigned long flags; BUG_ON(!dev_data->domain); - spin_lock_irqsave(&dev_data->domain->lock, flags); + domain = dev_data->domain; + + spin_lock_irqsave(&domain->lock, flags); if (dev_data->alias != dev) { alias_data = get_dev_data(dev_data->alias); @@ -1504,7 +1507,7 @@ static void __detach_device(struct device *dev) if (atomic_dec_and_test(&dev_data->bind)) do_detach(dev); - spin_unlock_irqrestore(&dev_data->domain->lock, flags); + spin_unlock_irqrestore(&domain->lock, flags); /* * If we run in passthrough mode the device must be assigned to the -- 1.6.6
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