From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1D9FEC433F5 for ; Thu, 10 Feb 2022 13:28:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242214AbiBJN2X (ORCPT ); Thu, 10 Feb 2022 08:28:23 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:55326 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242197AbiBJN2T (ORCPT ); Thu, 10 Feb 2022 08:28:19 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C8DB4BA0 for ; Thu, 10 Feb 2022 05:28:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=qgJ7BeTdHSxnO0s1F6v+Di4M//rT9yP6AOORlVtJCSI=; b=pDt7Kz1BNTg3Gif0QrECApPRwq t/zFCnya18pfeKuahfGbTny5QJloaHTjPTgQ/bHWSSq0ejUd7IEzW776dUIekV3nWgM3RDzCnyygU jCAh6agscdA2uUPKvEsEBjr+sykJ6LK8bXafhhGpkLdyMtXI1qHfewnm0j5mkzW/lC0+Q7Ut5v+Tg hycFoeofKLY2e5Q/TLn7Hw1vnXXQ+i2D0Jyqk4DP24VZ3QHEac+pqmbHPI241HgYCm7EfecpC2a1v XJ54dWQ5Ee/uit71wuIYXWqi9xfjCa9gkHaOZu4ttBqGzV31RU+HIcJlerIvdQI1L4bMYTFAqUoeU H5l3tTBA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nI9Tz-009Stf-7J; Thu, 10 Feb 2022 13:27:35 +0000 Date: Thu, 10 Feb 2022 13:27:35 +0000 From: Matthew Wilcox To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, ccross@google.com, sumit.semwal@linaro.org, mhocko@suse.com, dave.hansen@intel.com, keescook@chromium.org, kirill.shutemov@linux.intel.com, vbabka@suse.cz, hannes@cmpxchg.org, ebiederm@xmission.com, brauner@kernel.org, legion@kernel.org, ran.xiaokai@zte.com.cn, sashal@kernel.org, chris.hyser@oracle.com, dave@stgolabs.net, pcc@google.com, caoxiaofeng@yulong.com, david@redhat.com, gorcunov@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com, syzbot+aa7b3d4b35f9dc46a366@syzkaller.appspotmail.com Subject: Re: [PATCH v2 1/1] mm: fix use-after-free when anon vma name is used after vma is freed Message-ID: References: <20220210043215.42794-1-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220210043215.42794-1-surenb@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 09, 2022 at 08:32:15PM -0800, Suren Baghdasaryan wrote: > +void vma_anon_name_put(struct anon_vma_name *anon_name) > +{ > + kref_put(&anon_name->kref, vma_anon_name_free); > +} To agree with Michal, make this: if (anon_name) kref_put(&anon_name->kref, vma_anon_name_free); > > - error = madvise_update_vma(vma, prev, start, end, new_flags, > - vma_anon_name(vma)); > + anon_name = vma_anon_name_get(vma); > + if (anon_name) { > + error = madvise_update_vma(vma, prev, start, end, new_flags, > + anon_name->name); > + vma_anon_name_put(anon_name); > + } else { > + error = madvise_update_vma(vma, prev, start, end, new_flags, > + NULL); > + } And then this becomes: anon_name = vma_anon_name_get(vma); error = madvise_update_vma(vma, prev, start, end, new_flags, anon_name); vma_anon_name_put(anon_name);