drm/nouveau: usif_ioctl: ensure returns are initialized
diff mbox

Message ID 1435769495-2025-1-git-send-email-colin.king@canonical.com
State New
Headers show

Commit Message

Colin King July 1, 2015, 4:51 p.m. UTC
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
[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(-)

Comments

Colin King July 1, 2015, 5:18 p.m. UTC | #1
On 01/07/15 18:12, Emil Velikov wrote:
> On 1 July 2015 at 17:56, Ilia Mirkin <imirkin@alum.mit.edu> wrote:
>> 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?

Hrm, what about the case when ((vl) == 0 || ret == -ENOSYS) is false,
where is ret being set in that case?

>>
> I think I'm having deja-vu, but I do recall a similar mention to Ben.
> Although in my defence I've assumed that nvif_unpack was a function,
> as macros normally are normally all caps. Seems like the patch that
> capitalises nvif_unpack never made it upstream :'-(
> 
> Cheers,
> Emil
>

Patch
diff mbox

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;