Nouveau - Dec 2021 - [PATCH] drm/nouveau/core/object: Fix the uninitialized use of "type"

In function nvkm_ioctl_map(), the variable "type" could be
uninitialized if "nvkm_object_map()" returns error code, however,
it does not check the return value and directly use the "type" in
the if statement, which is potentially unsafe.

Cc: stable at vger.kernel.org
Fixes: 01326050391c ("drm/nouveau/core/object: allow arguments to be passed
to map function")
Signed-off-by: Yizhuo Zhai <yzhai003 at ucr.edu>
---
 drivers/gpu/drm/nouveau/nvkm/core/ioctl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nvkm/core/ioctl.c
b/drivers/gpu/drm/nouveau/nvkm/core/ioctl.c
index 735cb6816f10..4264d9d79783 100644
--- a/drivers/gpu/drm/nouveau/nvkm/core/ioctl.c
+++ b/drivers/gpu/drm/nouveau/nvkm/core/ioctl.c
@@ -266,6 +266,8 @@ nvkm_ioctl_map(struct nvkm_client *client,
 		ret = nvkm_object_map(object, data, size, &type,
 				      &args->v0.handle,
 				      &args->v0.length);
+		if (ret)
+			return ret;
 		if (type == NVKM_OBJECT_MAP_IO)
 			args->v0.type = NVIF_IOCTL_MAP_V0_IO;
 		else
-- 
2.25.1

Reviewed-by: Lyude Paul <lyude at redhat.com>

On Fri, 2021-12-17 at 18:56 -0800, Yizhuo Zhai wrote:
> In function nvkm_ioctl_map(), the variable "type" could be
> uninitialized if "nvkm_object_map()" returns error code, however,
> it does not check the return value and directly use the "type" in
> the if statement, which is potentially unsafe.
> 
> Cc: stable at vger.kernel.org
> Fixes: 01326050391c ("drm/nouveau/core/object: allow arguments to be
passed
> to map function")
> Signed-off-by: Yizhuo Zhai <yzhai003 at ucr.edu>
> ---
> ?drivers/gpu/drm/nouveau/nvkm/core/ioctl.c | 2 ++
> ?1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/nouveau/nvkm/core/ioctl.c
> b/drivers/gpu/drm/nouveau/nvkm/core/ioctl.c
> index 735cb6816f10..4264d9d79783 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/core/ioctl.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/core/ioctl.c
> @@ -266,6 +266,8 @@ nvkm_ioctl_map(struct nvkm_client *client,
> ????????????????ret = nvkm_object_map(object, data, size, &type,
> ????????????????????????????????????? &args->v0.handle,
> ????????????????????????????????????? &args->v0.length);
> +???????????????if (ret)
> +???????????????????????return ret;
> ????????????????if (type == NVKM_OBJECT_MAP_IO)
> ????????????????????????args->v0.type = NVIF_IOCTL_MAP_V0_IO;
> ????????????????else
-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat