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Commit b21602a8 authored by Ezequiel Garcia's avatar Ezequiel Garcia Committed by Greg Kroah-Hartman
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drm/vkms: Hold gem object while still in-use 



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: default avatar <syzbot+e3372a2afe1e7ef04bc7@syzkaller.appspotmail.com>
Signed-off-by: default avatarEzequiel Garcia <ezequiel@collabora.com>
Reviewed-by: default avatarRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: default avatarRodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200427214405.13069-1-ezequiel@collabora.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9c09a772

drivers/gpu/drm/vkms/vkms_drv.h

+0 −5
Original line number Diff line number Diff line
@@ -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,

drivers/gpu/drm/vkms/vkms_gem.c

+6 −5
Original line number Diff line number Diff line
@@ -95,7 +95,7 @@ vm_fault_t vkms_gem_fault(struct vm_fault *vmf) 
	return ret;

}



struct drm_gem_object *vkms_gem_create(struct drm_device *dev,

static struct drm_gem_object *vkms_gem_create(struct drm_device *dev,

					      struct drm_file *file,

					      u32 *handle,

					      u64 size)
@@ -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;