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drm/vkms: Hold gem object while still in-use 

commit 0ea2ea42b3 upstream.

We need to keep the reference to the drm_gem_object
until the last access by vkms_dumb_create.

Therefore, the put the object after it is used.

This fixes a use-after-free issue reported by syzbot.

While here, change vkms_gem_create() symbol to static.

Reported-and-tested-by: syzbot+e3372a2afe1e7ef04bc7@syzkaller.appspotmail.com
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200427214405.13069-1-ezequiel@collabora.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Ezequiel Garcia 2020-04-27 18:44:05 -03:00 committed by Greg Kroah-Hartman
parent 9c09a772ac
commit b21602a88e
2 changed files with 6 additions and 10 deletions
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5
drivers/gpu/drm/vkms/vkms_drv.h
View File

@ -121,11 +121,6 @@ struct drm_plane *vkms_plane_init(struct vkms_device *vkmsdev,
enum drm_plane_type type, int index);
/* Gem stuff */
struct drm_gem_object *vkms_gem_create(struct drm_device *dev,
struct drm_file *file,
u32 *handle,
u64 size);
vm_fault_t vkms_gem_fault(struct vm_fault *vmf);
int vkms_dumb_create(struct drm_file *file, struct drm_device *dev,

11
drivers/gpu/drm/vkms/vkms_gem.c
View File

@ -95,10 +95,10 @@ vm_fault_t vkms_gem_fault(struct vm_fault *vmf)
return ret;
}
struct drm_gem_object *vkms_gem_create(struct drm_device *dev,
struct drm_file *file,
u32 *handle,
u64 size)
static struct drm_gem_object *vkms_gem_create(struct drm_device *dev,
struct drm_file *file,
u32 *handle,
u64 size)
{
struct vkms_gem_object *obj;
int ret;
@ -111,7 +111,6 @@ struct drm_gem_object *vkms_gem_create(struct drm_device *dev,
return ERR_CAST(obj);
ret = drm_gem_handle_create(file, &obj->gem, handle);
drm_gem_object_put_unlocked(&obj->gem);
if (ret)
return ERR_PTR(ret);
@ -140,6 +139,8 @@ int vkms_dumb_create(struct drm_file *file, struct drm_device *dev,
args->size = gem_obj->size;
args->pitch = pitch;
drm_gem_object_put_unlocked(gem_obj);
DRM_DEBUG_DRIVER("Created object of size %lld\n", size);
return 0;