linux-kernel - [PATCH] drm/nouveau: usif_ioctl: ensure returns are initialized

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Date:	Wed,  1 Jul 2015 17:51:35 +0100
From:	Colin King <colin.king@...onical.com>
To:	David Airlie <airlied@...ux.ie>, Ben Skeggs <bskeggs@...hat.com>,
	dri-devel@...ts.freedesktop.org
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] drm/nouveau: usif_ioctl: ensure returns are initialized

From: Colin Ian King <colin.king@...onical.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@...onical.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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