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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 84E37C4360F for ; Wed, 3 Apr 2019 15:49:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F14B206DD for ; Wed, 3 Apr 2019 15:49:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727153AbfDCPtP (ORCPT ); Wed, 3 Apr 2019 11:49:15 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:43510 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726183AbfDCPtL (ORCPT ); Wed, 3 Apr 2019 11:49:11 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id AFD1380D; Wed, 3 Apr 2019 08:49:10 -0700 (PDT) Received: from fuggles.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F1BC33F68F; Wed, 3 Apr 2019 08:49:04 -0700 (PDT) Date: Wed, 3 Apr 2019 16:49:02 +0100 From: Will Deacon To: Jens Axboe Cc: Michael Ellerman , Arnd Bergmann , Andrew Morton , Richard Henderson , Ivan Kokshaysky , Matt Turner , Russell King , Catalin Marinas , Tony Luck , Fenghua Yu , Geert Uytterhoeven , Michal Simek , Ralf Baechle , Paul Burton , James Hogan , "James E . J . Bottomley" , Helge Deller , Benjamin Herrenschmidt , Paul Mackerras , Martin Schwidefsky , Heiko Carstens , Rich Felker , "David S . Miller" , Max Filippov , Firoz Khan , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org Subject: Re: [PATCH 2/2] arch: add pidfd and io_uring syscalls everywhere Message-ID: <20190403154902.GB16866@fuggles.cambridge.arm.com> References: <20190325143521.34928-1-arnd@arndb.de> <20190325144737.703921-1-arnd@arndb.de> <87tvff24a1.fsf@concordia.ellerman.id.au> <20190403111134.GA7159@fuggles.cambridge.arm.com> <9d673dfd-0051-3676-653e-6376430d73dd@kernel.dk> <20190403151932.GA16866@fuggles.cambridge.arm.com> <032faa2f-6317-75b6-8514-076ef1a244e8@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <032faa2f-6317-75b6-8514-076ef1a244e8@kernel.dk> User-Agent: Mutt/1.11.1+86 (6f28e57d73f2) () Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 03, 2019 at 09:39:52AM -0600, Jens Axboe wrote: > On 4/3/19 9:19 AM, Will Deacon wrote: > > On Wed, Apr 03, 2019 at 07:49:26AM -0600, Jens Axboe wrote: > >> On 4/3/19 5:11 AM, Will Deacon wrote: > >>> will@autoplooker:~/liburing/test$ ./io_uring_register > >>> RELIMIT_MEMLOCK: 67108864 (67108864) > >>> [ 35.477875] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000070 > >>> [ 35.478969] Mem abort info: > >>> [ 35.479296] ESR = 0x96000004 > >>> [ 35.479785] Exception class = DABT (current EL), IL = 32 bits > >>> [ 35.480528] SET = 0, FnV = 0 > >>> [ 35.480980] EA = 0, S1PTW = 0 > >>> [ 35.481345] Data abort info: > >>> [ 35.481680] ISV = 0, ISS = 0x00000004 > >>> [ 35.482267] CM = 0, WnR = 0 > >>> [ 35.482618] user pgtable: 4k pages, 48-bit VAs, pgdp = (____ptrval____) > >>> [ 35.483486] [0000000000000070] pgd=0000000000000000 > >>> [ 35.484041] Internal error: Oops: 96000004 [#1] PREEMPT SMP > >>> [ 35.484788] Modules linked in: > >>> [ 35.485311] CPU: 113 PID: 3973 Comm: io_uring_regist Not tainted 5.1.0-rc3-00012-g40b114779944 #1 > >>> [ 35.486712] Hardware name: linux,dummy-virt (DT) > >>> [ 35.487450] pstate: 20400005 (nzCv daif +PAN -UAO) > >>> [ 35.488228] pc : link_pwq+0x10/0x60 > >>> [ 35.488794] lr : apply_wqattrs_commit+0xe0/0x118 > >>> [ 35.489550] sp : ffff000017e2bbc0 > >> > >> Huh, this looks odd, it's crashing inside the wq setup. > > > > Enabling KASAN seems to indicate a double-free, which may well be related. > > Does this help? Yes, thanks for the quick patch. Feel free to add: Reported-by: Will Deacon Tested-by: Will Deacon if you spin a proper patch. Will > diff --git a/fs/io_uring.c b/fs/io_uring.c > index bbdbd56cf2ac..07d6ef195d05 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -2215,6 +2215,7 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg, > fput(ctx->user_files[i]); > > kfree(ctx->user_files); > + ctx->user_files = NULL; > ctx->nr_user_files = 0; > return ret; > } > > -- > Jens Axboe >