From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Date: Mon, 25 May 2020 11:43:19 -0500
Patch-mainline: v5.8-rc1
Subject: PCI: hv: Use struct_size() helper
Git-commit: d0684fd0bd79395e074dd668feee5d53b134b1a3
References: bsc#1204446

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct hv_dr_state {
	...
        struct hv_pcidev_description func[];
};

struct pci_bus_relations {
	...
        struct pci_function_description func[];
} __packed;

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.

So, replace the following forms:

offsetof(struct hv_dr_state, func) +
	(sizeof(struct hv_pcidev_description) *
	(relations->device_count))

offsetof(struct pci_bus_relations, func) +
	(sizeof(struct pci_function_description) *
	(bus_rel->device_count))

with:

struct_size(dr, func, relations->device_count)

and

struct_size(bus_rel, func, bus_rel->device_count)

respectively.

Link: https://lore.kernel.org/r/20200525164319.GA13596@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Olaf Hering <ohering@suse.de>
---
 drivers/pci/host/pci-hyperv.c | 22 +++------
 1 file changed, 8 insertions(+), 14 deletions(-)

--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1907,10 +1907,8 @@ static void hv_pci_devices_present(struct hv_pcibus_device *hbus,
 	struct hv_dr_state *dr;
 	int i;
 
-	dr = kzalloc(offsetof(struct hv_dr_state, func) +
-		     (sizeof(struct hv_pcidev_description) *
-		      (relations->device_count)), GFP_NOWAIT);
-
+	dr = kzalloc(struct_size(dr, func, relations->device_count),
+		     GFP_NOWAIT);
 	if (!dr)
 		return;
 
@@ -1944,10 +1942,8 @@ static void hv_pci_devices_present2(struct hv_pcibus_device *hbus,
 	struct hv_dr_state *dr;
 	int i;
 
-	dr = kzalloc(offsetof(struct hv_dr_state, func) +
-		     (sizeof(struct hv_pcidev_description) *
-		      (relations->device_count)), GFP_NOWAIT);
-
+	dr = kzalloc(struct_size(dr, func, relations->device_count),
+		     GFP_NOWAIT);
 	if (!dr)
 		return;
 
@@ -2132,9 +2128,8 @@ static void hv_pci_onchannelcallback(void *context)
 
 				bus_rel = (struct pci_bus_relations *)buffer;
 				if (bytes_recvd <
-				    offsetof(struct pci_bus_relations, func) +
-				    (sizeof(struct pci_function_description) *
-				     (bus_rel->device_count))) {
+					struct_size(bus_rel, func,
+						    bus_rel->device_count)) {
 					dev_err(&hbus->hdev->device,
 						"bus relations too small\n");
 					break;
@@ -2147,9 +2142,8 @@ static void hv_pci_onchannelcallback(void *context)
 
 				bus_rel2 = (struct pci_bus_relations2 *)buffer;
 				if (bytes_recvd <
-				    offsetof(struct pci_bus_relations2, func) +
-				    (sizeof(struct pci_function_description2) *
-				     (bus_rel2->device_count))) {
+					struct_size(bus_rel2, func,
+						    bus_rel2->device_count)) {
 					dev_err(&hbus->hdev->device,
 						"bus relations v2 too small\n");
 					break;