From: Ezequiel Garcia ezequiel@collabora.com
commit 0ea2ea42b31abc1141f2fd3911f952a97d401fcb 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-ezequie... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/vkms/vkms_drv.h | 5 ----- drivers/gpu/drm/vkms/vkms_gem.c | 11 ++++++----- 2 files changed, 6 insertions(+), 10 deletions(-)
--- a/drivers/gpu/drm/vkms/vkms_drv.h +++ b/drivers/gpu/drm/vkms/vkms_drv.h @@ -121,11 +121,6 @@ struct drm_plane *vkms_plane_init(struct 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, --- a/drivers/gpu/drm/vkms/vkms_gem.c +++ b/drivers/gpu/drm/vkms/vkms_gem.c @@ -97,10 +97,10 @@ vm_fault_t vkms_gem_fault(struct vm_faul 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; @@ -113,7 +113,6 @@ struct drm_gem_object *vkms_gem_create(s 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);
@@ -142,6 +141,8 @@ int vkms_dumb_create(struct drm_file *fi 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;