linux-kernel - [PATCH] iommu: Up front sanity check in the arm_lpae

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Date:   Sat, 5 Dec 2020 16:29:57 +0800
From:   Keqian Zhu <zhukeqian1@...wei.com>
To:     <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <iommu@...ts.linux-foundation.org>
CC:     Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        Catalin Marinas <catalin.marinas@....com>,
        James Morse <james.morse@....com>,
        "Suzuki K Poulose" <suzuki.poulose@....com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Mark Brown <broonie@...nel.org>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexios Zavras <alexios.zavras@...el.com>,
        <wanghaibin.wang@...wei.com>, <jiangkunkun@...wei.com>,
        Keqian Zhu <zhukeqian1@...wei.com>
Subject: [PATCH] iommu: Up front sanity check in the arm_lpae_map

... then we have more chance to detect wrong code logic.

Signed-off-by: Keqian Zhu <zhukeqian1@...wei.com>
---
 drivers/iommu/io-pgtable-arm.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index a7a9bc08dcd1..8ade72adab31 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -444,10 +444,6 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
 	arm_lpae_iopte prot;
 	long iaext = (s64)iova >> cfg->ias;
 
-	/* If no access, then nothing to do */
-	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
-		return 0;
-
 	if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
 		return -EINVAL;
 
@@ -456,6 +452,10 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
 	if (WARN_ON(iaext || paddr >> cfg->oas))
 		return -ERANGE;
 
+	/* If no access, then nothing to do */
+	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
+		return 0;
+
 	prot = arm_lpae_prot_to_pte(data, iommu_prot);
 	ret = __arm_lpae_map(data, iova, paddr, size, prot, lvl, ptep, gfp);
 	/*
-- 
2.23.0