Received: by 2002:a25:683:0:0:0:0:0 with SMTP id 125csp799303ybg; Wed, 10 Jun 2020 14:09:42 -0700 (PDT) X-Google-Smtp-Source: ABdhPJziBzxFkNJ/zPw7AlN1thxAmzccfIEN+deS6fE7/ozuHXjiJin6iRtHtSkjsHhtT5VsjemC X-Received: by 2002:a17:906:d78a:: with SMTP id pj10mr5456303ejb.50.1591823381920; Wed, 10 Jun 2020 14:09:41 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1591823381; cv=none; d=google.com; s=arc-20160816; b=nio5Zg8fM36yupjxMJIpLocTBm2aeJODWLhGLUnigmqQ1BU1ZdxApHRE7xpqjhWpmT 01owF/0+EXWr6/VS3GirwqTduEdCjuRnlJ5H6+pdpgj98vyKQfprNZNjckhrSm1Sx+Vc UABarXql1F5+0WlkwgXuJfM+gTcIsHhXHaOVfV7gfrsRyWNYJEeiMV2ObIeGYfBiGT1x RnLYtwHIuZhUNTUnt26VypM/pbU/Pp014kkZYsvEEq0ZYtuJoeifyRSV0B6efJOqxDpx AoG5+J9XPM238XOJPQdATaWi/ZUNUQFbP1JNDyMAKCceBMAg8kKY0GiSVWjdSSNvtaMq dTRQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:in-reply-to:content-disposition :mime-version:references:message-id:subject:cc:to:from:date; bh=rtz2vN7CFZQpJYvXEPS3Yq2YD2aJ8gz2xn4IR/MWg7k=; b=qRkPwfrFRDiu+Eo5cdee35KfTVUMdNy+9xC/rXYewhMeriUGD2xxaRCwZM+mKmRZBJ bynBh4nj5XdkAekBg0iREPTuXGzXJTOn8k9YTgjYjmR9OyJMyQoxG1R+XKFTgcwvDkEE JLQHpnsyAqzzm212w32GP9fBgy4It3wQuvtlRte6PV1FatrdAVUTP3fZlr7TrBwVTDMo 1ljQvlM/aIn32PORQuuHdoZ6XtwWBy9BqBjfL6uNWV82Lheafuim9FjmzPHLguULPGsc S4Pb9dIdljyqs6ThRKcl4mlLImuIkc6GgGeEOrFRF8wpcneYA770dICwsLwLM4iugNa7 StyA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id j1si431072edy.413.2020.06.10.14.09.19; Wed, 10 Jun 2020 14:09:41 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726702AbgFJRmD (ORCPT + 99 others); Wed, 10 Jun 2020 13:42:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37054 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726254AbgFJRmC (ORCPT ); Wed, 10 Jun 2020 13:42:02 -0400 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 33AB3C03E96B; Wed, 10 Jun 2020 10:42:02 -0700 (PDT) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.93 #3 (Red Hat Linux)) id 1jj4jY-006YSx-Ps; Wed, 10 Jun 2020 17:41:52 +0000 Date: Wed, 10 Jun 2020 18:41:52 +0100 From: Al Viro To: "Eric W. Biederman" Cc: Alexey Gladkov , syzbot , adobriyan@gmail.com, keescook@chromium.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [PATCH] proc: s_fs_info may be NULL when proc_kill_sb is called Message-ID: <20200610174152.GS23230@ZenIV.linux.org.uk> References: <0000000000002d7ca605a7b8b1c5@google.com> <20200610130422.1197386-1-gladkov.alexey@gmail.com> <87mu5azvxl.fsf@x220.int.ebiederm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87mu5azvxl.fsf@x220.int.ebiederm.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 10, 2020 at 12:12:54PM -0500, Eric W. Biederman wrote: > > { > > struct proc_fs_info *fs_info = proc_sb_info(sb); > > > > - if (fs_info->proc_self) > > - dput(fs_info->proc_self); > > + if (fs_info) { > > + if (fs_info->proc_self) > > + dput(fs_info->proc_self); > > > > - if (fs_info->proc_thread_self) > > - dput(fs_info->proc_thread_self); > > + if (fs_info->proc_thread_self) > > + dput(fs_info->proc_thread_self); > > + > > + put_pid_ns(fs_info->pid_ns); > > + kfree(fs_info); While we are at it, dput(NULL) is an explicit no-op.