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

Guoqing Jiang
2022-08-22T05:34:15Z

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

Thanks,
Guoqing