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md: Free resources in __md_stop

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commit 3e453522593d74a87cf68a38e14aa36ebca1dbcd upstream.

If md_run() fails after ->active_io is initialized, then percpu_ref_exit
is called in error path. However, later md_free_disk will call
percpu_ref_exit again which leads to a panic because of null pointer
dereference. It can also trigger this bug when resources are initialized
but are freed in error path, then will be freed again in md_free_disk.

BUG: kernel NULL pointer dereference, address: 0000000000000038
Oops: 0000 [#1] PREEMPT SMP
Workqueue: md_misc mddev_delayed_delete
RIP: 0010:free_percpu+0x110/0x630
Call Trace:
 <TASK>
 __percpu_ref_exit+0x44/0x70
 percpu_ref_exit+0x16/0x90
 md_free_disk+0x2f/0x80
 disk_release+0x101/0x180
 device_release+0x84/0x110
 kobject_put+0x12a/0x380
 kobject_put+0x160/0x380
 mddev_delayed_delete+0x19/0x30
 process_one_work+0x269/0x680
 worker_thread+0x266/0x640
 kthread+0x151/0x1b0
 ret_from_fork+0x1f/0x30

For creating raid device, md raid calls do_md_run->md_run, dm raid calls
md_run. We alloc those memory in md_run. For stopping raid device, md raid
calls do_md_stop->__md_stop, dm raid calls md_stop->__md_stop. So we can
free those memory resources in __md_stop.

Fixes: 72adae23a72c ("md: Change active_io to percpu")
Reported-and-tested-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Xiao Ni <xni@redhat.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Xiao Ni 2023-02-22 11:59:16 +08:00 committed by Greg Kroah-Hartman
parent ba6a70adb5
commit d9ece8c026
1 changed files with 5 additions and 8 deletions
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13
drivers/md/md.c
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@ -6277,6 +6277,11 @@ static void __md_stop(struct mddev *mddev)
mddev->to_remove = &md_redundancy_group;
module_put(pers->owner);
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
percpu_ref_exit(&mddev->writes_pending);
percpu_ref_exit(&mddev->active_io);
bioset_exit(&mddev->bio_set);
bioset_exit(&mddev->sync_set);
}
void md_stop(struct mddev *mddev)
@ -6288,9 +6293,6 @@ void md_stop(struct mddev *mddev)
*/
__md_stop_writes(mddev);
__md_stop(mddev);
percpu_ref_exit(&mddev->active_io);
bioset_exit(&mddev->bio_set);
bioset_exit(&mddev->sync_set);
}
EXPORT_SYMBOL_GPL(md_stop);
@ -7857,11 +7859,6 @@ static void md_free_disk(struct gendisk *disk)
{
struct mddev *mddev = disk->private_data;
percpu_ref_exit(&mddev->writes_pending);
percpu_ref_exit(&mddev->active_io);
bioset_exit(&mddev->bio_set);
bioset_exit(&mddev->sync_set);
mddev_free(mddev);
}