ACPI/IORT: Fix off-by-one check in iort_dev_find_its_id()

[ Upstream commit 5a46d3f71d5e5a9f82eabc682f996f1281705ac7 ]

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/
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
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>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 6b81746cd13c8358e4ca9288d330f6e18666f7e0..e5b1b3f1c23191a87cc4b8ddf339d6fac3e38cc5 100644 (file)
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -324,8 +324,8 @@ 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;
        }