linux-kernel - [PATCH 1/1] iommu/amd: fix incorrect error handling

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Date:   Sun, 23 Apr 2017 18:23:21 +0800
From:   Pan Bian <bianpan201602@....com>
To:     Joerg Roedel <joro@...tes.org>, iommu@...ts.linux-foundation.org
Cc:     linux-kernel@...r.kernel.org, Pan Bian <bianpan2016@....com>
Subject: [PATCH 1/1] iommu/amd: fix incorrect error handling

From: Pan Bian <bianpan2016@....com>

In function amd_iommu_bind_pasid(), the control flow jumps to label
out_free when pasid_state->mm and mm is NULL. And mmput(mm) is called.
In function mmput(mm), mm is referenced without validation. This will
result in a NULL dereference bug. This patch fixes the bug.

Signed-off-by: Pan Bian <bianpan2016@....com>
---
 drivers/iommu/amd_iommu_v2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index 0633439..6629c47 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -696,9 +696,9 @@ int amd_iommu_bind_pasid(struct pci_dev *pdev, int pasid,
 
 out_unregister:
 	mmu_notifier_unregister(&pasid_state->mn, mm);
+	mmput(mm);
 
 out_free:
-	mmput(mm);
 	free_pasid_state(pasid_state);
 
 out:
-- 
1.9.1