From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:40033 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756767Ab3J2CGj (ORCPT ); Mon, 28 Oct 2013 22:06:39 -0400 Date: Tue, 29 Oct 2013 10:05:55 +0800 From: Liu Bo To: Pedro Fonseca Cc: linux-btrfs@vger.kernel.org Subject: Re: Null pointer dereference bug in btrfs_find_all_root Message-ID: <20131029020554.GA32338@localhost.localdomain> Reply-To: bo.li.liu@oracle.com References: <526E8A83.4030201@mpi-sws.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <526E8A83.4030201@mpi-sws.org> Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi, On Mon, Oct 28, 2013 at 05:02:11PM +0100, Pedro Fonseca wrote: > Hi, > > I've encountered a few NULL pointer dereference bugs while running a > custom test case on btrfs (kernel 3.11.1), inside a QEMU based VM. > > Btrfs was statically compiled and the btrfs filesystem was mounted > on one or two loop devices. All cases occurred during execution of a > "filesystem balance" operation and while another file system > operation was concurrently executed. In one case the other operation > was a "mknod" and in another it was a "filesystem show" operation. I'm wonderring that if there is anything like 'aborted transaction' in the dmesg log besides this NULL pointer dereference? -liubo > > In all cases the NULL pointer dereference occurred in the > "btrfs_find_all_roots" function and all cases produced a bug report > similar to the one bellow: > > >[ 138.573390] BUG: unable to handle kernel NULL pointer > >dereference at (null) > >[ 138.573390] IP: [] ulist_next+0x4/0x26 > >[ 138.573390] *pde = 00000000 > >[ 138.573390] Oops: 0000 [#1] SMP > >[ 138.573390] Modules linked in: loop rtc_cmos pcspkr tpm_tis > >freq_table mperf i2c_piix4 > >[ 138.573390] CPU: 0 PID: 2794 Comm: btrfs-endio-wri Not tainted > >3.11.1 #2 > >[ 138.573390] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007 > >[ 138.573390] task: c5dea6b0 ti: c5e12000 task.ti: c5e12000 > >[ 138.573390] EIP: 0060:[] EFLAGS: 00000246 CPU: 0 > >[ 138.573390] EIP is at ulist_next+0x4/0x26 > >[ 138.573390] EAX: 00000000 EBX: 00000000 ECX: d9c29e38 EDX: c5e13da4 > >[ 138.573390] ESI: 00000000 EDI: c5e13e00 EBP: c5e13d94 ESP: c5e13d90 > >[ 138.573390] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 > >[ 138.573390] CR0: 8005003b CR2: 00000000 CR3: 059d8000 CR4: 00000690 > >[ 138.573390] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 > >[ 138.573390] DR6: 00000000 DR7: 00000000 > >[ 138.573390] Stack: > >[ 138.573390] 00000000 c5e13db4 c12fe7b8 de4d1000 d9cead48 > >00000001 010dd000 deeab810 > >[ 138.573390] 00000001 c5e13e10 c12fe8cf 00af2000 00000000 > >00000000 00000003 c5e13e00 > >[ 138.573390] deeabe00 00000000 00000003 deeab800 de4d1000 > >d9cead48 de4d14b8 de4d14b8 > >[ 138.573390] Call Trace: > >[ 138.573390] [] btrfs_find_all_roots+0x88/0xa6 > >[ 138.573390] [] iterate_extent_inodes+0xf9/0x1b2 > >[ 138.573390] [] iterate_inodes_from_logical+0x88/0x97 > >[ 138.573390] [] ? record_extent_backrefs+0x8b/0x8b > >[ 138.573390] [] record_extent_backrefs+0x50/0x8b > >[ 138.573390] [] ? record_extent_backrefs+0x8b/0x8b > >[ 138.573390] [] btrfs_finish_ordered_io+0x77e/0x876 > >[ 138.573390] [] finish_ordered_fn+0xb/0xd > >[ 138.573390] [] worker_loop+0x111/0x3ec > >[ 138.573390] [] ? default_wake_function+0xb/0xd > >[ 138.573390] [] kthread+0x90/0x95 > >[ 138.573390] [] ? btrfs_queue_worker+0x1c8/0x1c8 > >[ 138.573390] [] ret_from_kernel_thread+0x1b/0x28 > >[ 138.573390] [] ? kthread_freezable_should_stop+0x4f/0x4f > >[ 138.573390] Code: 5b 5e 5f 5d c3 90 90 90 55 8d 50 10 89 e5 c7 > >00 00 00 00 00 89 50 08 c7 40 04 10 00 00 00 c7 40 0c 00 00 00 00 > >5d c3 55 89 e5 53 <8b> 08 85 c9 74 15 8b 1a 85 db 78 0f 39 cb 73 > >0b 6b cb 1c 43 03 > >[ 138.573390] EIP: [] ulist_next+0x4/0x26 SS:ESP 0068:c5e13d90 > >[ 138.573390] CR2: 0000000000000000 > >[ 138.573390] ---[ end trace 626899e11111abbe ]--- > >[ 138.573390] BUG: unable to handle kernel NULL pointer > >dereference at (null) > >[ 138.573390] IP: [] ulist_next+0x4/0x26 > >[ 138.573390] *pde = 00000000 > >[ 138.573390] Oops: 0000 [#2] SMP > >[ 138.573390] Modules linked in: loop rtc_cmos pcspkr tpm_tis > >freq_table mperf i2c_piix4 > >[ 138.573390] CPU: 1 PID: 2793 Comm: btrfs-endio-wri Tainted: G > >D 3.11.1 #2 > >[ 138.573390] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007 > >[ 138.573390] task: c59cc190 ti: dedc8000 task.ti: dedc8000 > >[ 138.573390] EIP: 0060:[] EFLAGS: 00000246 CPU: 1 > >[ 138.573390] EIP is at ulist_next+0x4/0x26 > >[ 138.573390] EAX: 00000000 EBX: 00000000 ECX: d9c296c8 EDX: dedc9da4 > >[ 138.573390] ESI: 00000000 EDI: dedc9e00 EBP: dedc9d94 ESP: dedc9d90 > >[ 138.573390] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 > >[ 138.573390] CR0: 8005003b CR2: 00000000 CR3: 03ebe000 CR4: 00000690 > >[ 138.573390] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 > >[ 138.573390] DR6: 00000000 DR7: 00000000 > >[ 138.573390] Stack: > >[ 138.573390] 00000000 dedc9db4 c12fe7b8 de4d1000 d9ceaf50 > >00000001 00dea000 de4c6410 > >[ 138.573390] 00000001 dedc9e10 c12fe8cf 00af2000 00000000 > >00000000 00000005 dedc9e00 > >[ 138.573390] de4c6c00 00000000 00000005 de4c6400 de4d1000 > >d9ceaf50 de4d14b8 c5e13de8 > >[ 138.573390] Call Trace: > >[ 138.573390] [] btrfs_find_all_roots+0x88/0xa6 > >[ 138.573390] [] iterate_extent_inodes+0xf9/0x1b2 > >[ 138.573390] [] iterate_inodes_from_logical+0x88/0x97 > >[ 138.573390] [] ? record_extent_backrefs+0x8b/0x8b > >[ 138.573390] [] record_extent_backrefs+0x50/0x8b > >[ 138.573390] [] ? record_extent_backrefs+0x8b/0x8b > >[ 138.573390] [] btrfs_finish_ordered_io+0x77e/0x876 > >[ 138.573390] [] finish_ordered_fn+0xb/0xd > >[ 138.573390] [] worker_loop+0x111/0x3ec > >[ 138.573390] [] ? default_wake_function+0xb/0xd > >[ 138.573390] [] kthread+0x90/0x95 > >[ 138.573390] [] ? btrfs_queue_worker+0x1c8/0x1c8 > >[ 138.573390] [] ret_from_kernel_thread+0x1b/0x28 > >[ 138.573390] [] ? kthread_freezable_should_stop+0x4f/0x4f > >[ 138.573390] Code: 5b 5e 5f 5d c3 90 90 90 55 8d 50 10 89 e5 c7 > >00 00 00 00 00 89 50 08 c7 40 04 10 00 00 00 c7 40 0c 00 00 00 00 > >5d c3 55 89 e5 53 <8b> 08 85 c9 74 15 8b 1a 85 db 78 0f 39 cb 73 > >0b 6b cb 1c 43 03 > >[ 138.573390] EIP: [] ulist_next+0x4/0x26 SS:ESP 0068:dedc9d90 > >[ 138.573390] CR2: 0000000000000000 > >[ 138.573390] ---[ end trace 626899e11111abbf ]---