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 F3F20C04A68 for ; Wed, 27 Jul 2022 18:27:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234292AbiG0S1O (ORCPT ); Wed, 27 Jul 2022 14:27:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39658 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239173AbiG0S0y (ORCPT ); Wed, 27 Jul 2022 14:26:54 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id C774E9C25F for ; Wed, 27 Jul 2022 10:25:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1658942734; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=xI0tNVEQ4QF856krL574dmH7GWXh+Ia0PGG2VcgVgaA=; b=SLdvHojSg70zObt5Rci6dlQvXF+RdF/lKhpUDrr4BkfOhgKeHTRkVAm3RYGFlLoQnoFeSQ ZX+V9qyIKU8QhBO+kxANMVG7i9vkGaopbzKfHGYVULt8rBSuZWwYxMKiael3hg0ir1FQM8 f6NjzlW6HJv2mTEDduFMb5pkzJ2Z0i8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-590-KGze-vjcM3CPjB45oqV-HA-1; Wed, 27 Jul 2022 13:25:21 -0400 X-MC-Unique: KGze-vjcM3CPjB45oqV-HA-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E9CE085A586; Wed, 27 Jul 2022 17:25:20 +0000 (UTC) Received: from fedora (unknown [10.40.192.210]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BFE1840315E; Wed, 27 Jul 2022 17:25:19 +0000 (UTC) Date: Wed, 27 Jul 2022 19:25:17 +0200 From: Lukas Czerner To: Tadeusz Struk Cc: Theodore Ts'o , Jan Kara , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+bd13648a53ed6933ca49@syzkaller.appspotmail.com Subject: Re: [PATCH] ext4: try to flush inline data before calling BUG in writepages Message-ID: <20220727172517.bv2bflydy2urqttv@fedora> References: <983bb802-d883-18d4-7945-dbfa209c1cc8@linaro.org> <20220726224428.407887-1-tadeusz.struk@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220726224428.407887-1-tadeusz.struk@linaro.org> X-Scanned-By: MIMEDefang 2.85 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Tue, Jul 26, 2022 at 03:44:28PM -0700, Tadeusz Struk wrote: > Fix a syzbot issue, which triggers a BUG in ext4_writepags. > The syzbot creates and monuts an ext4 fs image on /dev/loop0. > The image is corrupted, which is probably the source of the > problems, but the mount operation finishes successfully. > Then the repro program creates a file on the mounted fs, and > eventually it writes a buff of 22 zero bytes to it as below: > > memfd_create("syzkaller", 0) = 3 > ftruncate(3, 2097152) = 0 > pwrite64(3, " \0\0\0\0\2\0\0\31\0\0\0\220\1\0\0\17\0\0\0\0\0\0\0\2\0\0\0\6\0\0\0"..., 102, 1024) = 102 > pwrite64(3, "\0\0\0\0\0\0\0\0\0\0\0\0\202\343g$\306\363L\252\204n\322\345'p3x\1\0@", 31, 1248) = 31 > pwrite64(3, "\2\0\0\0\3\0\0\0\4\0\0\0\31\0\17\0\3\0\4\0\0\0\0\0\0\0\0\0\17\0.i", 32, 4096) = 32 > pwrite64(3, "\177\0\0\0\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377"..., 4098, 8192) = 4098 > pwrite64(3, "\355A\0\0\20\0\0\0\332\364e_\333\364e_\333\364e_\0\0\0\0\0\0\4\0\200\0\0\0"..., 61, 17408) = 61 > openat(AT_FDCWD, "/dev/loop0", O_RDWR) = 4 > ioctl(4, LOOP_SET_FD, 3) = 0 > mkdir("./file0", 0777) = -1 EEXIST (File exists) > mount("/dev/loop0", "./file0", "ext4", 0, ",errors=continue") = 0 > openat(AT_FDCWD, "./file0", O_RDONLY|O_DIRECTORY) = 5 > ioctl(4, LOOP_CLR_FD) = 0 > close(4) = 0 > close(3) = 0 > chdir("./file0") = 0 > creat("./bus", 000) = 3 > open("./bus", O_RDWR|O_CREAT|O_NONBLOCK|O_SYNC|O_DIRECT|O_LARGEFILE|O_NOATIME, 000) = 4 > openat(AT_FDCWD, "/proc/self/exe", O_RDONLY) = 6 > sendfile(4, 6, NULL, 2147483663) = 1638400 > open("./bus", O_RDWR|O_CREAT|O_SYNC|O_NOATIME, 000) = 7 > write(7, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 22) > > This triggers a BUG in ext4_writepages(), where it checks if > the inode has inline data, just before deleting it: > > kernel BUG at fs/ext4/inode.c:2721! > invalid opcode: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 359 Comm: repro Not tainted 5.19.0-rc8-00001-g31ba1e3b8305-dirty #15 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014 > RIP: 0010:ext4_writepages+0x363d/0x3660 > RSP: 0018:ffffc90000ccf260 EFLAGS: 00010293 > RAX: ffffffff81e1abcd RBX: 0000008000000000 RCX: ffff88810842a180 > RDX: 0000000000000000 RSI: 0000008000000000 RDI: 0000000000000000 > RBP: ffffc90000ccf650 R08: ffffffff81e17d58 R09: ffffed10222c680b > R10: dfffe910222c680c R11: 1ffff110222c680a R12: ffff888111634128 > R13: ffffc90000ccf880 R14: 0000008410000000 R15: 0000000000000001 > FS: 00007f72635d2640(0000) GS:ffff88811b000000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000565243379180 CR3: 000000010aa74000 CR4: 0000000000150eb0 > Call Trace: > > do_writepages+0x397/0x640 > filemap_fdatawrite_wbc+0x151/0x1b0 > file_write_and_wait_range+0x1c9/0x2b0 > ext4_sync_file+0x19e/0xa00 > vfs_fsync_range+0x17b/0x190 > ext4_buffered_write_iter+0x488/0x530 > ext4_file_write_iter+0x449/0x1b90 > vfs_write+0xbcd/0xf40 > ksys_write+0x198/0x2c0 > __x64_sys_write+0x7b/0x90 > do_syscall_64+0x3d/0x90 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > This can be prevented by forcing the inline data to be converted > and/or flushed beforehand. > This patch adds a call to ext4_convert_inline_data() just before > the BUG, which fixes the issue. > > Link: https://syzkaller.appspot.com/bug?id=a1e89d09bbbcbd5c4cb45db230ee28c822953984 > Reported-by: syzbot+bd13648a53ed6933ca49@syzkaller.appspotmail.com > Signed-off-by: Tadeusz Struk > --- > fs/ext4/inode.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 84c0eb55071d..de2aa2e79052 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -2717,6 +2717,10 @@ static int ext4_writepages(struct address_space *mapping, > ret = PTR_ERR(handle); > goto out_writepages; > } > + > + if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) > + WARN_ON(ext4_convert_inline_data(inode)); > + Hi Tadeusz, I don't think this is the right fix. We're in ext4_writepages, so at this point I don't think an inode should have any actual inline data in it. If it does it's a bug and the question is how did this get here? The inode is likely corrupted and it should have been noticed earliler and it should never get here. -Lukas > BUG_ON(ext4_test_inode_state(inode, > EXT4_STATE_MAY_INLINE_DATA)); > ext4_destroy_inline_data(handle, inode); > -- > 2.37.1 >