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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CF47C433EF for ; Thu, 10 Feb 2022 13:28:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C3ED76B0075; Thu, 10 Feb 2022 08:28:19 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BEF4B6B007B; Thu, 10 Feb 2022 08:28:19 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ADD666B007D; Thu, 10 Feb 2022 08:28:19 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0148.hostedemail.com [216.40.44.148]) by kanga.kvack.org (Postfix) with ESMTP id 9F36D6B0075 for ; Thu, 10 Feb 2022 08:28:19 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 39919181AC9C6 for ; Thu, 10 Feb 2022 13:28:19 +0000 (UTC) X-FDA: 79126949118.27.345041D Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf27.hostedemail.com (Postfix) with ESMTP id 7B2864000E for ; Thu, 10 Feb 2022 13:28:18 +0000 (UTC) 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> X-Stat-Signature: iegktsbh93s8m8qeunruyzcd3mcz4cdd Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=pDt7Kz1B; spf=none (imf27.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 7B2864000E X-HE-Tag: 1644499698-248681 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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);