This is a note to let you know that I've just added the patch titled
md: Free resources in __md_stop
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
md-free-resources-in-__md_stop.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3e453522593d74a87cf68a38e14aa36ebca1dbcd Mon Sep 17 00:00:00 2001
From: Xiao Ni <xni@xxxxxxxxxx>
Date: Wed, 22 Feb 2023 11:59:16 +0800
Subject: md: Free resources in __md_stop
From: Xiao Ni <xni@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Xiao Ni <xni@xxxxxxxxxx>
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/md.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6277,6 +6277,11 @@ static void __md_stop(struct mddev *mdde
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
{
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);
}
Patches currently in stable-queue which might be from xni@xxxxxxxxxx are
queue-6.1/md-free-resources-in-__md_stop.patch
queue-6.1/md-factor-out-is_md_suspended-helper.patch
queue-6.1/md-change-active_io-to-percpu.patch
queue-6.1/md-add-error_handlers-for-raid0-and-linear.patch
