linux-kernel - [PATCH 3/3] iommu/vt-d: skip invalid RMRR entries

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Message-Id: <20191211194606.87940-4-brho@google.com>
Date:   Wed, 11 Dec 2019 14:46:06 -0500
From:   Barret Rhoden <brho@...gle.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Joerg Roedel <joro@...tes.org>,
        Yian Chen <yian.chen@...el.com>,
        Sohil Mehta <sohil.mehta@...el.com>
Cc:     linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        x86@...nel.org
Subject: [PATCH 3/3] iommu/vt-d: skip invalid RMRR entries

The VT-d docs specify requirements for the RMRR entries base and end
(called 'Limit' in the docs) addresses.

This commit will cause the DMAR processing to skip any RMRR entries
that do not meet these requirements with the expectation that firmware
is giving us junk.

Signed-off-by: Barret Rhoden <brho@...gle.com>
---
 drivers/iommu/intel-iommu.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index f7e09244c9e4..11322fefb883 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4307,6 +4307,18 @@ static void __init init_iommu_pm_ops(void)
 static inline void init_iommu_pm_ops(void) {}
 #endif	/* CONFIG_PM */
 
+static int rmrr_validity_check(struct acpi_dmar_reserved_memory *rmrr)
+{
+	if ((rmrr->base_address & PAGE_MASK) ||
+	    (rmrr->end_address <= rmrr->base_address) ||
+	    ((rmrr->end_address - rmrr->base_address + 1) & PAGE_MASK)) {
+		pr_err(FW_BUG "Broken RMRR base: %#018Lx end: %#018Lx\n",
+		       rmrr->base_address, rmrr->end_address);
+		return -EINVAL;
+	}
+	return 0;
+}
+
 int __init dmar_parse_one_rmrr(struct acpi_dmar_header *header, void *arg)
 {
 	struct acpi_dmar_reserved_memory *rmrr;
@@ -4314,7 +4326,7 @@ int __init dmar_parse_one_rmrr(struct acpi_dmar_header *header, void *arg)
 	int ret;
 
 	rmrr = (struct acpi_dmar_reserved_memory *)header;
-	ret = arch_rmrr_sanity_check(rmrr);
+	ret = rmrr_validity_check(rmrr) || arch_rmrr_sanity_check(rmrr);
 	if (ret)
 		return 0;
 
-- 
2.24.0.525.g8f36a354ae-goog