iommu/amd: Fix incorrect error handling in amd_iommu_bind_pasid()

commit 73dbd4a4230216b6a5540a362edceae0c9b4876b upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index f8ed8c9..a0b4ac6 100644 (file)
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -695,9 +695,9 @@ out_clear_state:
 
 out_unregister:
        mmu_notifier_unregister(&pasid_state->mn, mm);
+       mmput(mm);
 
 out_free:
-       mmput(mm);
        free_pasid_state(pasid_state);
 
 out: