linux-kernel - [PATCH 5.14 048/100] iommu/vt-d: Fix PASID leak in intel_svm_unbind

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Date:   Fri, 24 Sep 2021 14:43:57 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <jroedel@...e.de>,
        Sasha Levin <sashal@...nel.org>,
        Dave Jiang <dave.jiang@...el.com>
Subject: [PATCH 5.14 048/100] iommu/vt-d: Fix PASID leak in intel_svm_unbind_mm()

From: Fenghua Yu <fenghua.yu@...el.com>

[ Upstream commit a21518cb23a3c7d49bafcb59862fd389fd829d4b ]

The mm->pasid will be used in intel_svm_free_pasid() after load_pasid()
during unbinding mm. Clearing it in load_pasid() will cause PASID cannot
be freed in intel_svm_free_pasid().

Additionally mm->pasid was updated already before load_pasid() during pasid
allocation. No need to update it again in load_pasid() during binding mm.
Don't update mm->pasid to avoid the issues in both binding mm and unbinding
mm.

Fixes: 4048377414162 ("iommu/vt-d: Use iommu_sva_alloc(free)_pasid() helpers")
Reported-and-tested-by: Dave Jiang <dave.jiang@...el.com>
Co-developed-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
Link: https://lore.kernel.org/r/20210826215918.4073446-1-fenghua.yu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
Link: https://lore.kernel.org/r/20210828070622.2437559-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iommu/intel/svm.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 4b9b3f35ba0e..ceeca633a5f9 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -516,9 +516,6 @@ static void load_pasid(struct mm_struct *mm, u32 pasid)
 {
 	mutex_lock(&mm->context.lock);
 
-	/* Synchronize with READ_ONCE in update_pasid(). */
-	smp_store_release(&mm->pasid, pasid);
-
 	/* Update PASID MSR on all CPUs running the mm's tasks. */
 	on_each_cpu_mask(mm_cpumask(mm), _load_pasid, NULL, true);
 
-- 
2.33.0