[PATCH] drm/i915/kvmgt: Use struct_size() helper

Gustavo A. R. Silva
2019-05-24T17:14:21Z

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes, in particular in the
context in which this code is being used.

So, replace the following form:

sizeof(*sparse) + (nr_areas * sizeof(*sparse->areas)

with:

struct_size(sparse, areas, sparse->nr_areas)

and so on...

Also, notice that variable size is unnecessary, hence it is removed.

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
drivers/gpu/drm/i915/gvt/kvmgt.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 144301b778df..9674738b89df 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -1306,7 +1306,6 @@ static long intel_vgpu_ioctl(struct mdev_device *mdev, unsigned int cmd,
unsigned int i;
int ret;
struct vfio_region_info_cap_sparse_mmap *sparse = NULL;
- size_t size;
int nr_areas = 1;
int cap_type_id;

@@ -1349,9 +1348,8 @@ static long intel_vgpu_ioctl(struct mdev_device *mdev, unsigned int cmd,
VFIO_REGION_INFO_FLAG_WRITE;
info.size = gvt_aperture_sz(vgpu->gvt);

- size = sizeof(*sparse) +
- (nr_areas * sizeof(*sparse->areas));
- sparse = kzalloc(size, GFP_KERNEL);
+ sparse = kzalloc(struct_size(sparse, areas, nr_areas),
+ GFP_KERNEL);
if (!sparse)
return -ENOMEM;

@@ -1416,9 +1414,9 @@ static long intel_vgpu_ioctl(struct mdev_device *mdev, unsigned int cmd,
switch (cap_type_id) {
case VFIO_REGION_INFO_CAP_SPARSE_MMAP:
ret = vfio_info_add_capability(&caps,
- &sparse->header, sizeof(*sparse) +
- (sparse->nr_areas *
- sizeof(*sparse->areas)));
+ &sparse->header,
+ struct_size(sparse, areas,
+ sparse->nr_areas));
if (ret) {
kfree(sparse);
return ret;
--
2.21.0