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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2F56C43387 for ; Fri, 28 Dec 2018 21:09:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C717820856 for ; Fri, 28 Dec 2018 21:09:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726046AbeL1VJm (ORCPT ); Fri, 28 Dec 2018 16:09:42 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:59840 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725945AbeL1VJm (ORCPT ); Fri, 28 Dec 2018 16:09:42 -0500 Received: from localhost.localdomain (c-24-6-170-16.hsd1.ca.comcast.net [24.6.170.16]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id F3193B1D; Fri, 28 Dec 2018 21:09:39 +0000 (UTC) Date: Fri, 28 Dec 2018 13:09:38 -0800 From: Andrew Morton To: syzbot Cc: darrick.wong@oracle.com, hannes@cmpxchg.org, hughd@google.com, jack@suse.cz, josef@toxicpanda.com, jrdr.linux@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, sfr@canb.auug.org.au, syzkaller-bugs@googlegroups.com, willy@infradead.org Subject: Re: KASAN: use-after-free Read in filemap_fault Message-Id: <20181228130938.c9e42c213cdcc35a93dd0dac@linux-foundation.org> In-Reply-To: <000000000000b57d19057e1b383d@google.com> References: <000000000000b57d19057e1b383d@google.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 28 Dec 2018 12:51:04 -0800 syzbot wrote: > Hello, > > syzbot found the following crash on: uh-oh. Josef, could you please take a look? : page = find_get_page(mapping, offset); : if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) { : /* : * We found the page, so try async readahead before : * waiting for the lock. : */ : fpin = do_async_mmap_readahead(vmf, page); : } else if (!page) { : /* No page in the page cache at all */ : fpin = do_sync_mmap_readahead(vmf); : count_vm_event(PGMAJFAULT); : count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT); vmf->vma has been freed at this point. : ret = VM_FAULT_MAJOR; : retry_find: : page = pagecache_get_page(mapping, offset, : FGP_CREAT|FGP_FOR_MMAP, : vmf->gfp_mask); : if (!page) { : if (fpin) : goto out_retry; : return vmf_error(-ENOMEM); : } : }