iommu/vt-d: Avoid use of NULL after WARN_ON_ONCE

[ Upstream commit 60f030f7418d3f1d94f2fb207fe3080e1844630b ]

There is a WARN_ON_ONCE to catch an unlikely situation when
domain_remove_dev_pasid can't find the `pasid`. In case it nevertheless
happens we must avoid using a NULL pointer.

Signed-off-by: Kees Bakker <kees@ijzerbout.nl>
Link: https://lore.kernel.org/r/20241218201048.E544818E57E@bout3.ijzerbout.nl
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Amelia Crate <acrate@waldn.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 667407974e23a7a8900a7eaa91e8e628716ef474..c799cc67db34e5ba47492417bca9c590dabdc4cf 100644 (file)
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4328,13 +4328,14 @@ static void intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid,
                        break;
                }
        }
-       WARN_ON_ONCE(!dev_pasid);
        spin_unlock_irqrestore(&dmar_domain->lock, flags);
 
        cache_tag_unassign_domain(dmar_domain, dev, pasid);
        domain_detach_iommu(dmar_domain, iommu);
-       intel_iommu_debugfs_remove_dev_pasid(dev_pasid);
-       kfree(dev_pasid);
+       if (!WARN_ON_ONCE(!dev_pasid)) {
+               intel_iommu_debugfs_remove_dev_pasid(dev_pasid);
+               kfree(dev_pasid);
+       }
        intel_pasid_tear_down_entry(iommu, dev, pasid, false);
        intel_drain_pasid_prq(dev, pasid);
 }