Re: [PATCH 5.10 055/545] md-raid: destroy the bitmap after destroying the thread

Guoqing Jiang
2022-08-29T02:32:40Z

On 8/22/22 2:26 PM, Greg Kroah-Hartman wrote:
> On Mon, Aug 22, 2022 at 01:33:47PM +0800, Guoqing Jiang wrote:
>>
>> On 8/19/22 11:37 PM, Greg Kroah-Hartman wrote:
>>> From: Mikulas Patocka <mpatocka@redhat.com>
>>>
>>> commit e151db8ecfb019b7da31d076130a794574c89f6f upstream.
>>>
>>> When we ran the lvm test "shell/integrity-blocksize-3.sh" on a kernel with
>>> kasan, we got failure in write_page.
>>>
>>> The reason for the failure is that md_bitmap_destroy is called before
>>> destroying the thread and the thread may be waiting in the function
>>> write_page for the bio to complete. When the thread finishes waiting, it
>>> executes "if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))", which
>>> triggers the kasan warning.
>>>
>>> Note that the commit 48df498daf62 that caused this bug claims that it is
>>> neede for md-cluster, you should check md-cluster and possibly find
>>> another bugfix for it.
>>>
>>> BUG: KASAN: use-after-free in write_page+0x18d/0x680 [md_mod]
>>> Read of size 8 at addr ffff889162030c78 by task mdX_raid1/5539
>>>
>>> CPU: 10 PID: 5539 Comm: mdX_raid1 Not tainted 5.19.0-rc2 #1
>>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
>>> Call Trace:
>>> <TASK>
>>> dump_stack_lvl+0x34/0x44
>>> print_report.cold+0x45/0x57a
>>> ? __lock_text_start+0x18/0x18
>>> ? write_page+0x18d/0x680 [md_mod]
>>> kasan_report+0xa8/0xe0
>>> ? write_page+0x18d/0x680 [md_mod]
>>> kasan_check_range+0x13f/0x180
>>> write_page+0x18d/0x680 [md_mod]
>>> ? super_sync+0x4d5/0x560 [dm_raid]
>>> ? md_bitmap_file_kick+0xa0/0xa0 [md_mod]
>>> ? rs_set_dev_and_array_sectors+0x2e0/0x2e0 [dm_raid]
>>> ? mutex_trylock+0x120/0x120
>>> ? preempt_count_add+0x6b/0xc0
>>> ? preempt_count_sub+0xf/0xc0
>>> md_update_sb+0x707/0xe40 [md_mod]
>>> md_reap_sync_thread+0x1b2/0x4a0 [md_mod]
>>> md_check_recovery+0x533/0x960 [md_mod]
>>> raid1d+0xc8/0x2a20 [raid1]
>>> ? var_wake_function+0xe0/0xe0
>>> ? psi_group_change+0x411/0x500
>>> ? preempt_count_sub+0xf/0xc0
>>> ? _raw_spin_lock_irqsave+0x78/0xc0
>>> ? __lock_text_start+0x18/0x18
>>> ? raid1_end_read_request+0x2a0/0x2a0 [raid1]
>>> ? preempt_count_sub+0xf/0xc0
>>> ? _raw_spin_unlock_irqrestore+0x19/0x40
>>> ? del_timer_sync+0xa9/0x100
>>> ? try_to_del_timer_sync+0xc0/0xc0
>>> ? _raw_spin_lock_irqsave+0x78/0xc0
>>> ? __lock_text_start+0x18/0x18
>>> ? __list_del_entry_valid+0x68/0xa0
>>> ? finish_wait+0xa3/0x100
>>> md_thread+0x161/0x260 [md_mod]
>>> ? unregister_md_personality+0xa0/0xa0 [md_mod]
>>> ? _raw_spin_lock_irqsave+0x78/0xc0
>>> ? prepare_to_wait_event+0x2c0/0x2c0
>>> ? unregister_md_personality+0xa0/0xa0 [md_mod]
>>> kthread+0x148/0x180
>>> ? kthread_complete_and_exit+0x20/0x20
>>> ret_from_fork+0x1f/0x30
>>> </TASK>
>>>
>>> Allocated by task 5522:
>>> kasan_save_stack+0x1e/0x40
>>> __kasan_kmalloc+0x80/0xa0
>>> md_bitmap_create+0xa8/0xe80 [md_mod]
>>> md_run+0x777/0x1300 [md_mod]
>>> raid_ctr+0x249c/0x4a30 [dm_raid]
>>> dm_table_add_target+0x2b0/0x620 [dm_mod]
>>> table_load+0x1c8/0x400 [dm_mod]
>>> ctl_ioctl+0x29e/0x560 [dm_mod]
>>> dm_compat_ctl_ioctl+0x7/0x20 [dm_mod]
>>> __do_compat_sys_ioctl+0xfa/0x160
>>> do_syscall_64+0x90/0xc0
>>> entry_SYSCALL_64_after_hwframe+0x46/0xb0
>>>
>>> Freed by task 5680:
>>> kasan_save_stack+0x1e/0x40
>>> kasan_set_track+0x21/0x40
>>> kasan_set_free_info+0x20/0x40
>>> __kasan_slab_free+0xf7/0x140
>>> kfree+0x80/0x240
>>> md_bitmap_free+0x1c3/0x280 [md_mod]
>>> __md_stop+0x21/0x120 [md_mod]
>>> md_stop+0x9/0x40 [md_mod]
>>> raid_dtr+0x1b/0x40 [dm_raid]
>>> dm_table_destroy+0x98/0x1e0 [dm_mod]
>>> __dm_destroy+0x199/0x360 [dm_mod]
>>> dev_remove+0x10c/0x160 [dm_mod]
>>> ctl_ioctl+0x29e/0x560 [dm_mod]
>>> dm_compat_ctl_ioctl+0x7/0x20 [dm_mod]
>>> __do_compat_sys_ioctl+0xfa/0x160
>>> do_syscall_64+0x90/0xc0
>>> entry_SYSCALL_64_after_hwframe+0x46/0xb0
>>>
>>> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
>>> Cc: stable@vger.kernel.org
>>> Fixes: 48df498daf62 ("md: move bitmap_destroy to the beginning of __md_stop")
>>> Signed-off-by: Song Liu <song@kernel.org>
>>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>>> ---
>>> drivers/md/md.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> --- a/drivers/md/md.c
>>> +++ b/drivers/md/md.c
>>> @@ -6278,11 +6278,11 @@ static void mddev_detach(struct mddev *m
>>> static void __md_stop(struct mddev *mddev)
>>> {
>>> struct md_personality *pers = mddev->pers;
>>> - md_bitmap_destroy(mddev);
>>> mddev_detach(mddev);
>>> /* Ensure ->event_work is done */
>>> if (mddev->event_work.func)
>>> flush_workqueue(md_misc_wq);
>>> + md_bitmap_destroy(mddev);
>>> spin_lock(&mddev->lock);
>>> mddev->pers = NULL;
>>> spin_unlock(&mddev->lock);
>> Pls consider drop this one from stable per the link given it cause issue for
>> md-cluster.
>>
>> https://lore.kernel.org/linux-raid/a6657e08-b6a7-358b-2d2a-0ac37d49d23a@linux.dev/T/#m95ac225cab7409f66c295772483d091084a6d470
> I will just take the fixup patch when it hits Linus's tree as this
> commit is already in the following releases:
> 5.10.137 5.15.61 5.18.18 5.19.2

It is reverted by the commit.

1d258758cf06 Revert "md-raid: destroy the bitmap after destroying the
thread"

And the original problem should be fixed with this one.

0dd84b319352 md: call __md_stop_writes in md_stop

Please consider take the two patches, I assume they can be applied
directly, otherwise I will send them later.

Thanks,
Guoqing