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x86/amd-iommu: Fix NULL pointer dereference in __detach_device()

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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>
This commit is contained in:
Joerg Roedel 2010-01-22 16:45:31 +01:00
parent d91afd15b0
commit 2ca762790c
1 changed files with 5 additions and 2 deletions
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7
arch/x86/kernel/amd_iommu.c
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@ -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