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From:   Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To:     linux-acpi@vger.kernel.org
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Will Deacon <will@kernel.org>,
        Hanjun Guo <guohanjun@huawei.com>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Robin Murphy <robin.murphy@arm.com>,
        LKML <linux-kernel@vger.kernel.org>,
        LAKML <linux-arm-kernel@lists.infradead.org>
Subject: [PATCH] ACPI/IORT: Fix off-by-one check in iort_dev_find_its_id()
Date:   Mon, 22 Jul 2019 17:25:48 +0100
Message-Id: <20190722162548.23610-1-lorenzo.pieralisi@arm.com>
MIME-Version: 1.0
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Sender: linux-kernel-owner@vger.kernel.org
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Static analysis identified that index comparison against ITS entries in
iort_dev_find_its_id() is off by one.

Update the comparison condition and clarify the resulting error
message.

Fixes: 4bf2efd26d76 ("ACPI: Add new IORT functions to support MSI domain handling")
Link: https://lore.kernel.org/linux-arm-kernel/20190613065410.GB16334@mwanda/
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Will Deacon <will@kernel.org>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
---
 drivers/acpi/arm64/iort.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 15dbfd657d82..5a7551d060f2 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -611,8 +611,8 @@ static int iort_dev_find_its_id(struct device *dev, u32 req_id,
 
 	/* Move to ITS specific data */
 	its = (struct acpi_iort_its_group *)node->node_data;
-	if (idx > its->its_count) {
-		dev_err(dev, "requested ITS ID index [%d] is greater than available [%d]\n",
+	if (idx >= its->its_count) {
+		dev_err(dev, "requested ITS ID index [%d] overruns ITS entries [%d]\n",
 			idx, its->its_count);
 		return -ENXIO;
 	}
-- 
2.21.0