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 34E2CECAAD3 for ; Thu, 1 Sep 2022 23:25:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234800AbiIAXZH (ORCPT ); Thu, 1 Sep 2022 19:25:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53474 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231447AbiIAXZD (ORCPT ); Thu, 1 Sep 2022 19:25:03 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB40613F11; Thu, 1 Sep 2022 16:25:01 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5257162028; Thu, 1 Sep 2022 23:25:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7CDA6C433D6; Thu, 1 Sep 2022 23:25:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1662074700; bh=3Ei2pJxNHEj7Ms4tUmMY4vQ3bWZICi1bGNA88E3kO3U=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=zNHLDPV6huB6ldajXdDKZJKTucg41vNQy1eDgNGzo6nSdipYamio1gvgjT2LJMsIL 81HbuA8Ueqo5zDQi71TpbbiUn6wi2SPV5NXXmeo6T6uDk27V0YTO5S+YXmw98mBTsL +70Eq5tndj9TjEClRfrdME66CqB9ha620mnml22c= Date: Thu, 1 Sep 2022 16:24:59 -0700 From: Andrew Morton To: syzbot Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, willy@infradead.org Subject: Re: [syzbot] UBSAN: array-index-out-of-bounds in truncate_inode_pages_range Message-Id: <20220901162459.431c49b3925e99ddb448e1b3@linux-foundation.org> In-Reply-To: <000000000000117c7505e7927cb4@google.com> References: <000000000000117c7505e7927cb4@google.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 31 Aug 2022 17:13:36 -0700 syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 89b749d8552d Merge tag 'fbdev-for-6.0-rc3' of git://git.ke.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=14b9661b080000 > kernel config: https://syzkaller.appspot.com/x/.config?x=911efaff115942bb > dashboard link: https://syzkaller.appspot.com/bug?extid=5867885efe39089b339b > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > userspace arch: i386 > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+5867885efe39089b339b@syzkaller.appspotmail.com > > ntfs3: loop0: Different NTFS' sector size (1024) and media sector size (512) > ntfs3: loop0: RAW NTFS volume: Filesystem size 0.00 Gb > volume size 0.00 Gb. Mount in read-only > ================================================================================ > UBSAN: array-index-out-of-bounds in mm/truncate.c:366:18 > index 254 is out of range for type 'long unsigned int [15]' That's index = indices[folio_batch_count(&fbatch) - 1] + 1; I looked. I see no way in which fbatch.nr got a value of 255. I must say, the the code looks rather hacky. Isn't there a more type-friendly way of doing this?