[PATCH AUTOSEL 4.19 30/42] ACPI/IORT: Fix off-by-one check in iort_dev_find_its_id()

From: Sasha Levin
Date: Fri Aug 02 2019 - 09:24:16 EST

From: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>

[ 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

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@xxxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Hanjun Guo <guohanjun@xxxxxxxxxx>
Cc: Sudeep Holla <sudeep.holla@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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 43c2615434b48..e11b5da6f828f 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -616,8 +616,8 @@ 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;