iommu/vt-d: Fix dereference of pointer info before it is null checked

The assignment of iommu from info->iommu occurs before info is null checked
hence leading to a potential null pointer dereference issue. Fix this by
assigning iommu and checking if iommu is null after null checking info.

Addresses-Coverity: ("Dereference before null check")
Fixes: 4c82b88696ac ("iommu/vt-d: Allocate/register iopf queue for sva devices")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20210611135024.32781-1-colin.king@canonical.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index bd93c7ec879eee5f78e0f9eda1a788303bb0297b..76a58b8ad6c3890d5b37f4621dd56c3edd3ca5f5 100644 (file)
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -5329,10 +5329,14 @@ static int intel_iommu_disable_auxd(struct device *dev)
 static int intel_iommu_enable_sva(struct device *dev)
 {
        struct device_domain_info *info = get_domain_info(dev);
-       struct intel_iommu *iommu = info->iommu;
+       struct intel_iommu *iommu;
        int ret;
 
-       if (!info || !iommu || dmar_disabled)
+       if (!info || dmar_disabled)
+               return -EINVAL;
+
+       iommu = info->iommu;
+       if (!iommu)
                return -EINVAL;
 
        if (!(iommu->flags & VTD_FLAG_SVM_CAPABLE))