linux-kernel - [RFC V2 25/37] mm, x86, dmem: fix estimation of reserved page for vaddr_get

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Date:   Mon,  7 Dec 2020 19:31:18 +0800
From:   yulei.kernel@...il.com
To:     linux-mm@...ck.org, akpm@...ux-foundation.org,
        linux-fsdevel@...r.kernel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, naoya.horiguchi@....com,
        viro@...iv.linux.org.uk, pbonzini@...hat.com
Cc:     joao.m.martins@...cle.com, rdunlap@...radead.org,
        sean.j.christopherson@...el.com, xiaoguangrong.eric@...il.com,
        kernellwp@...il.com, lihaiwei.kernel@...il.com,
        Yulei Zhang <yuleixzhang@...cent.com>,
        Chen Zhuo <sagazchen@...cent.com>
Subject: [RFC V2 25/37] mm, x86, dmem: fix estimation of reserved page for vaddr_get_pfn()

From: Yulei Zhang <yuleixzhang@...cent.com>

Fix estimation of reserved page for vaddr_get_pfn() and
check 'ret' before checking writable permission

Signed-off-by: Chen Zhuo <sagazchen@...cent.com>
Signed-off-by: Yulei Zhang <yuleixzhang@...cent.com>
---
 drivers/vfio/vfio_iommu_type1.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 67e8276..c465d1a 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -471,6 +471,10 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
 		if (ret == -EAGAIN)
 			goto retry;
 
+		if (!ret && (prot & IOMMU_WRITE) &&
+		    !(vma->vm_flags & VM_WRITE))
+			ret = -EFAULT;
+
 		if (!ret && !is_invalid_reserved_pfn(*pfn))
 			ret = -EFAULT;
 	}
-- 
1.8.3.1