Messages in this thread | | | Date | Mon, 25 May 2020 01:05:37 +0100 | From | Al Viro <> | Subject | Re: [PATCH 2/5] seccomp: Introduce addfd ioctl to seccomp user notifier |
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On Sun, May 24, 2020 at 04:39:39PM -0700, Sargun Dhillon wrote: > +static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd) > +{ > + int ret; > + > + /* > + * Remove the notification, and reset the list pointers, indicating > + * that it has been handled. > + */ > + list_del_init(&addfd->list); > + > + ret = security_file_receive(addfd->file); > + if (ret) > + goto out; > + > + if (addfd->fd >= 0) { > + ret = replace_fd(addfd->fd, addfd->file, addfd->flags); > + if (ret >= 0) > + fput(addfd->file); > + } else { > + ret = get_unused_fd_flags(addfd->flags); > + if (ret >= 0) > + fd_install(ret, addfd->file);
Bad refcounting rules. *IF* we go with anything of that sort (and I'm not convinced that the entire series makes sense), it's better to have more uniform rules re reference consumption/disposal.
Make the destructor of addfd *ALWAYS* drop its reference. And have this function go
if (addfd->fd >= 0) { ret = replace_fd(addfd->fd, addfd->file, addfd->flags); } else { ret = get_unused_fd_flags(addfd->flags); if (ret >= 0) fd_install(ret, get_file(addfd->file)); }
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