On Sun, Aug 26, 2018 at 11:47 AM, Gustavo A. R. Silva gustavo@embeddedor.com wrote:

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 foo { int stuff; void *entry[]; };

instance = devm_kzalloc(dev, sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

or, like in this particular case:

size = sizeof(struct foo) + sizeof(void *) * count; instance = devm_kzalloc(dev, size, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper:

instance = devm_kzalloc(dev, struct_size(instance, entry, count), GFP_KERNEL);

This issue was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva gustavo@embeddedor.com

Reviewed-by: Kees Cook keescook@chromium.org

-Kees

---

drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c index 1359e5c..cf64e4d 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c @@ -32,6 +32,7 @@ #include <linux/of_device.h> #include <linux/pm_runtime.h> #include <linux/component.h> +#include <linux/overflow.h>

#include <linux/reset.h> #include <linux/delay.h> @@ -1561,7 +1562,6 @@ static int vop_bind(struct device *dev, struct device *master, void *data) struct drm_device *drm_dev = data; struct vop *vop; struct resource *res;

•   size_t alloc_size;
    int ret, irq;
  
    vop_data = of_device_get_match_data(dev);
  

@@ -1569,8 +1569,8 @@ static int vop_bind(struct device *dev, struct device *master, void *data) return -ENODEV;

    /* Allocate vop struct and its vop_win array */

•   alloc_size = sizeof(*vop) + sizeof(*vop->win) * vop_data->win_size;
  

•   vop = devm_kzalloc(dev, alloc_size, GFP_KERNEL);
  

•   vop = devm_kzalloc(dev, struct_size(vop, win, vop_data->win_size),
  

•                      GFP_KERNEL);
    if (!vop)
            return -ENOMEM;
  
  

-- 2.7.4