Re: [PATCH] drm/nouveau: usif_ioctl: ensure returns are initialized

On Wed, Jul 1, 2015 at 12:51 PM, Colin King colin.king@canonical.com wrote:

From: Colin Ian King colin.king@canonical.com

Various usif_ioctl helper functions do not initialize the return variable ret and some of the error handling return paths just return garbage values that were on the stack (or in a register). I believe that in all the cases, the initial ret variable should be set to -EINVAL and subsequent paths through these helper functions set it appropriately otherwise.

Found via static analysis using cppcheck:

[drivers/gpu/drm/nouveau/nouveau_usif.c:138]: (error) Uninitialized variable: ret

It sure would seem that way, wouldn't it?

#define nvif_unpack(d,vl,vh,m) ({ \ if ((vl) == 0 || ret == -ENOSYS) { \ int _size = sizeof(d); \ if (_size <= size && (d).version >= (vl) && \ (d).version <= (vh)) { \ data = (u8 *)data + _size; \ size = size - _size; \ ret = ((m) || !size) ? 0 : -E2BIG; \ } else { \ ret = -ENOSYS; \ } \ } \ (ret == 0); \ })

So actually it does get initialized, and I guess cppcheck doesn't know about macros?

[drivers/gpu/drm/nouveau/nouveau_usif.c:179]: (error) Uninitialized variable: ret [drivers/gpu/drm/nouveau/nouveau_usif.c:202]: (error) Uninitialized variable: ret [drivers/gpu/drm/nouveau/nouveau_usif.c:241]: (error) Uninitialized variable: ret [drivers/gpu/drm/nouveau/nouveau_usif.c:157]: (error) Uninitialized variable: ret [drivers/gpu/drm/nouveau/nouveau_usif.c:288]: (error) Uninitialized variable: ret

Signed-off-by: Colin Ian King colin.king@canonical.com

drivers/gpu/drm/nouveau/nouveau_usif.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_usif.c b/drivers/gpu/drm/nouveau/nouveau_usif.c index cb1182d..01b50a2 100644 --- a/drivers/gpu/drm/nouveau/nouveau_usif.c +++ b/drivers/gpu/drm/nouveau/nouveau_usif.c @@ -129,7 +129,7 @@ usif_notify_new(struct drm_file *f, void *data, u32 size, void *argv, u32 argc) struct nvif_notify_req_v0 v0; } *req; struct usif_notify *ntfy;

•   int ret;
  

•   int ret = -EINVAL;
  
    if (nvif_unpack(args->v0, 0, 0, true)) {
            if (usif_notify_find(f, args->v0.index))
  

@@ -170,7 +170,7 @@ usif_notify_del(struct drm_file *f, void *data, u32 size, void *argv, u32 argc) struct nvif_ioctl_ntfy_del_v0 v0; } *args = data; struct usif_notify *ntfy;

•   int ret;
  

•   int ret = -EINVAL;
  
    if (nvif_unpack(args->v0, 0, 0, true)) {
            if (!(ntfy = usif_notify_find(f, args->v0.index)))
  

@@ -193,7 +193,7 @@ usif_notify_get(struct drm_file *f, void *data, u32 size, void *argv, u32 argc) struct nvif_ioctl_ntfy_del_v0 v0; } *args = data; struct usif_notify *ntfy;

•   int ret;
  

•   int ret = -EINVAL;
  
    if (nvif_unpack(args->v0, 0, 0, true)) {
            if (!(ntfy = usif_notify_find(f, args->v0.index)))
  

@@ -232,7 +232,7 @@ usif_notify_put(struct drm_file *f, void *data, u32 size, void *argv, u32 argc) struct nvif_ioctl_ntfy_put_v0 v0; } *args = data; struct usif_notify *ntfy;

•   int ret;
  

•   int ret = -EINVAL;
  
    if (nvif_unpack(args->v0, 0, 0, true)) {
            if (!(ntfy = usif_notify_find(f, args->v0.index)))
  

@@ -269,7 +269,7 @@ usif_object_new(struct drm_file *f, void *data, u32 size, void *argv, u32 argc) struct nvif_ioctl_new_v0 v0; } *args = data; struct usif_object *object;

•   int ret;
  

•   int ret = -EINVAL;
  
    if (!(object = kmalloc(sizeof(*object), GFP_KERNEL)))
            return -ENOMEM;
  

-- 2.1.4

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