linux-kernel - [PATCH AUTOSEL 6.13 11/16] iommu/vt-d: Avoid use of NULL after WARN_ON

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Message-Id: <20250126150720.961959-11-sashal@kernel.org>
Date: Sun, 26 Jan 2025 10:07:13 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Kees Bakker <kees@...erbout.nl>,
	Lu Baolu <baolu.lu@...ux.intel.com>,
	Joerg Roedel <jroedel@...e.de>,
	Sasha Levin <sashal@...nel.org>,
	dwmw2@...radead.org,
	joro@...tes.org,
	will@...nel.org,
	iommu@...ts.linux.dev
Subject: [PATCH AUTOSEL 6.13 11/16] iommu/vt-d: Avoid use of NULL after WARN_ON_ONCE

From: Kees Bakker <kees@...erbout.nl>

[ 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@...erbout.nl>
Link: https://lore.kernel.org/r/20241218201048.E544818E57E@bout3.ijzerbout.nl
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iommu/intel/iommu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 79e0da9eb626c..8f75c11a3ec48 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4090,13 +4090,14 @@ void domain_remove_dev_pasid(struct iommu_domain *domain,
 			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);
+	}
 }
 
 static void intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid,
-- 
2.39.5