There's two references floating around here (for the object reference, not the handle_count reference, that's a different thing):
- The temporary reference held by vgem_gem_create, acquired by creating the object and released by calling drm_gem_object_put_unlocked. - The reference held by the object handle, created by drm_gem_handle_create. This one generally outlives the function, except if a 2nd thread races with a GEM_CLOSE ioctl call. So usually everything is correct, except in that race case, where the access to gem_object->size could be looking at freed data already. Which again isn't a real problem (userspace shot its feet off already with the race, we could return garbage), but maybe someone can exploit this as an information leak. Cc: Dan Carpenter <[email protected]> Cc: Hillf Danton <[email protected]> Cc: Reported-by: [email protected] Cc: [email protected] Cc: Emil Velikov <[email protected]> Cc: Daniel Vetter <[email protected]> Cc: Sean Paul <[email protected]> Cc: Chris Wilson <[email protected]> Cc: Eric Anholt <[email protected]> Cc: Sam Ravnborg <[email protected]> Cc: Rob Clark <[email protected]> Signed-off-by: Daniel Vetter <[email protected]> --- drivers/gpu/drm/vgem/vgem_drv.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c index 5bd60ded3d81..909eba43664a 100644 --- a/drivers/gpu/drm/vgem/vgem_drv.c +++ b/drivers/gpu/drm/vgem/vgem_drv.c @@ -196,9 +196,10 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev, return ERR_CAST(obj); ret = drm_gem_handle_create(file, &obj->base, handle); - drm_gem_object_put_unlocked(&obj->base); - if (ret) + if (ret) { + drm_gem_object_put_unlocked(&obj->base); return ERR_PTR(ret); + } return &obj->base; } @@ -221,7 +222,9 @@ static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev, args->size = gem_object->size; args->pitch = pitch; - DRM_DEBUG("Created object of size %lld\n", size); + drm_gem_object_put_unlocked(gem_object); + + DRM_DEBUG("Created object of size %llu\n", args->size); return 0; } -- 2.24.1 _______________________________________________ dri-devel mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/dri-devel
