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 56AAAC4321E for ; Tue, 29 Nov 2022 13:57:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D39F26B0074; Tue, 29 Nov 2022 08:57:06 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id CEA276B0075; Tue, 29 Nov 2022 08:57:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BD9986B0078; Tue, 29 Nov 2022 08:57:06 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id B1FA16B0074 for ; Tue, 29 Nov 2022 08:57:06 -0500 (EST) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 9A6501C6787 for ; Tue, 29 Nov 2022 09:08:48 +0000 (UTC) X-FDA: 80185904736.25.6D479EB Received: from r3-23.sinamail.sina.com.cn (r3-23.sinamail.sina.com.cn [202.108.3.23]) by imf04.hostedemail.com (Postfix) with ESMTP id CE78E40004 for ; Tue, 29 Nov 2022 09:08:46 +0000 (UTC) Received: from unknown (HELO localhost.localdomain)([114.249.57.238]) by sina.com (172.16.97.23) with ESMTP id 6385CB8C0000D6D4; Tue, 29 Nov 2022 17:06:22 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com X-SMAIL-MID: 19827654920277 From: Hillf Danton To: Al Viro Cc: syzbot , akpm@linux-foundation.org, dan.j.williams@intel.com, hch@lst.de, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, willy@infradead.org Subject: Re: [syzbot] WARNING in iov_iter_revert (3) Date: Tue, 29 Nov 2022 17:08:31 +0800 Message-Id: <20221129090831.6281-1-hdanton@sina.com> In-Reply-To: References: <000000000000519d0205ee4ba094@google.com> <000000000000f5ecad05ee8fccf0@google.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1669712928; a=rsa-sha256; cv=none; b=tElibMl9edmaYWTpqBhIZuK4yqqzZ+PjPjlXLIT0TJGOMaoKkRwk7IT6HxxDahE8sr2SZx zW4MtGnZuP3SouXOgifP40+7PmwpRnBcrG+Jt727toPIjg/eiv5Wt2WQ5MzJvZezkXO6dB Ib9loL2z3YxWy9+NjsZkehsCwdnrXxg= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf04.hostedemail.com: domain of hdanton@sina.com designates 202.108.3.23 as permitted sender) smtp.mailfrom=hdanton@sina.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1669712928; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Z6MFAZFSBr75QlGRGdGPMz2pIYsSb6tZbY/b5281824=; b=TvQI+BQ+tqYurphE8DHw4wyYq9exJGAkukv8oKAon5KSz/Iv+cXiXzFg6f9eaGxckKucfH hub3Q58Lz5R+CPW6VM49SwB+znCbdNkryHBUznqxsb8MoXFT1/+mVQsyfRu2KzwEumktFP Hue5bZUfiVepwcCMmxmeM3icyPJjrXw= X-Rspamd-Queue-Id: CE78E40004 Authentication-Results: imf04.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf04.hostedemail.com: domain of hdanton@sina.com designates 202.108.3.23 as permitted sender) smtp.mailfrom=hdanton@sina.com X-Rspamd-Server: rspam12 X-Rspam-User: X-Stat-Signature: 1qatwcoi6horcoi65i97tsmsp5k46wpa X-HE-Tag: 1669712926-873402 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 29 Nov 2022 04:04:35 +0000 Al Viro > On Mon, Nov 28, 2022 at 02:57:49PM -0800, syzbot wrote: > > syzbot has found a reproducer for the following issue on: > > [snip] > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17219fbb880000 > > "syz_mount_image$ntfs3(" followed by arseloads of garbage. And the thing > conspiciously missing? Why, any ntfs3 maintainers in Cc... Or lists, > for that matter... > > > generic_file_read_iter+0x3d4/0x540 mm/filemap.c:2804 > > do_iter_read+0x6e3/0xc10 fs/read_write.c:796 > > vfs_readv fs/read_write.c:916 [inline] > > do_preadv+0x1f4/0x330 fs/read_write.c:1008 > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 > > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > At a guess - something's screwed in ntfs3 ->direct_IO() (return value, most > likely). 2798 retval = mapping->a_ops->direct_IO(iocb, iter); 2799 if (retval >= 0) { 2800 iocb->ki_pos += retval; 2801 count -= retval; 2802 } 2803 if (retval != -EIOCBQUEUED) 2804 iov_iter_revert(iter, count - iov_iter_count(iter)); 2805 2806 /* 2807 * Btrfs can have a short DIO read if we encounter 2808 * compressed extents, so if there was an error, or if 2809 * we've already read everything we wanted to, or if 2810 * there was a short read because we hit EOF, go ahead 2811 * and return. Otherwise fallthrough to buffered io for 2812 * the rest of the read. Buffered reads will not work for 2813 * DAX files, so don't bother trying. 2814 */ 2815 if (retval < 0 || !count || IS_DAX(inode)) 2816 return retval; 2817 if (iocb->ki_pos >= i_size_read(inode)) 2818 return retval; If ntfs3 is supposed to do nothing wrong with retval set to 5, why is iov_iter_revert() invoked? Is it correct to check -EIOCBQUEUED only if the direct_IO callback returns error? Hillf