linux-kernel - [PATCH 2/2] iommu/vt-d: Check if domain->pgd was allocated

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Date:   Tue, 16 Jul 2019 22:38:06 +0100
From:   Dmitry Safonov <dima@...sta.com>
To:     linux-kernel@...r.kernel.org
Cc:     Dmitry Safonov <0x7f454c46@...il.com>,
        Dmitry Safonov <dima@...sta.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Joerg Roedel <joro@...tes.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        iommu@...ts.linux-foundation.org
Subject: [PATCH 2/2] iommu/vt-d: Check if domain->pgd was allocated

There is a couple of places where on domain_init() failure domain_exit()
is called. While currently domain_init() can fail only if
alloc_pgtable_page() has failed.

Make domain_exit() check if domain->pgd present, before calling
domain_unmap(), as it theoretically should crash on clearing pte entries
in dma_pte_clear_level().

Cc: David Woodhouse <dwmw2@...radead.org>
Cc: Joerg Roedel <joro@...tes.org>
Cc: Lu Baolu <baolu.lu@...ux.intel.com>
Cc: iommu@...ts.linux-foundation.org
Signed-off-by: Dmitry Safonov <dima@...sta.com>
---
 drivers/iommu/intel-iommu.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 6d1510284d21..698cc40355ef 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1835,7 +1835,6 @@ static inline int guestwidth_to_adjustwidth(int gaw)
 
 static void domain_exit(struct dmar_domain *domain)
 {
-	struct page *freelist;
 
 	/* Remove associated devices and clear attached or cached domains */
 	domain_remove_dev_info(domain);
@@ -1843,9 +1842,12 @@ static void domain_exit(struct dmar_domain *domain)
 	/* destroy iovas */
 	put_iova_domain(&domain->iovad);
 
-	freelist = domain_unmap(domain, 0, DOMAIN_MAX_PFN(domain->gaw));
+	if (domain->pgd) {
+		struct page *freelist;
 
-	dma_free_pagelist(freelist);
+		freelist = domain_unmap(domain, 0, DOMAIN_MAX_PFN(domain->gaw));
+		dma_free_pagelist(freelist);
+	}
 
 	free_domain_mem(domain);
 }
-- 
2.22.0