From 73dbd4a4230216b6a5540a362edceae0c9b4876b Mon Sep 17 00:00:00 2001
From: Pan Bian <bianpan2016@163.com>
Date: Sun, 23 Apr 2017 18:23:21 +0800
Subject: [PATCH] iommu/amd: Fix incorrect error handling in
 amd_iommu_bind_pasid()

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@163.com>
Fixes: f0aac63b873b ('iommu/amd: Don't hold a reference to mm_struct')
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 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 063343909b0d1..6629c472eafd8 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: