[PATCH v2 2/2] ACPI: NFIT: use struct_size() helper

[Yu Liao <liaoyu15@huawei.com>]

Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows that,
in the worst scenario, could lead to heap overflows.

Signed-off-by: Yu Liao <liaoyu15@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/acpi/nfit/core.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 305f590c54a8..2f7217600307 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -712,8 +712,7 @@ static bool add_spa(struct acpi_nfit_desc *acpi_desc,
 		}
 	}
 
-	nfit_spa = devm_kzalloc(dev, sizeof(*nfit_spa) + sizeof_spa(spa),
-			GFP_KERNEL);
+	nfit_spa = devm_kzalloc(dev, struct_size(nfit_spa, spa, 1), GFP_KERNEL);
 	if (!nfit_spa)
 		return false;
 	INIT_LIST_HEAD(&nfit_spa->list);
@@ -741,7 +740,7 @@ static bool add_memdev(struct acpi_nfit_desc *acpi_desc,
 			return true;
 		}
 
-	nfit_memdev = devm_kzalloc(dev, sizeof(*nfit_memdev) + sizeof(*memdev),
+	nfit_memdev = devm_kzalloc(dev, struct_size(nfit_memdev, memdev, 1),
 			GFP_KERNEL);
 	if (!nfit_memdev)
 		return false;
@@ -812,8 +811,7 @@ static bool add_dcr(struct acpi_nfit_desc *acpi_desc,
 			return true;
 		}
 
-	nfit_dcr = devm_kzalloc(dev, sizeof(*nfit_dcr) + sizeof(*dcr),
-			GFP_KERNEL);
+	nfit_dcr = devm_kzalloc(dev, struct_size(nfit_dcr, dcr, 1), GFP_KERNEL);
 	if (!nfit_dcr)
 		return false;
 	INIT_LIST_HEAD(&nfit_dcr->list);
@@ -855,7 +853,7 @@ static size_t sizeof_idt(struct acpi_nfit_interleave *idt)
 {
 	if (idt->header.length < sizeof(*idt))
 		return 0;
-	return sizeof(*idt) + sizeof(u32) * idt->line_count;
+	return struct_size(idt, line_offset, idt->line_count);
 }
 
 static bool add_idt(struct acpi_nfit_desc *acpi_desc,
-- 
2.25.1