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

[Greg Kroah-Hartman]

On Mon, Aug 29, 2022 at 10:32:30AM +0800, Guoqing Jiang wrote:
> 
> 
> 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@xxxxxxxxxx>
> > > > 
> > > > 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@xxxxxxxxxx>
> > > > Cc: stable@xxxxxxxxxxxxxxx
> > > > Fixes: 48df498daf62 ("md: move bitmap_destroy to the beginning of __md_stop")
> > > > Signed-off-by: Song Liu <song@xxxxxxxxxx>
> > > > Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
> > > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > > > ---
> > > >    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@xxxxxxxxx/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.

Great, that worked, all now queued up!

greg k-h