2021-10-18 10:35:46

by Zqiang

Subject: [PATCH v2] block: fix incorrect references to disk objects

When adding partitions to the disk, the reference count of the disk
object is increased. then alloc partition device and called
device_add(), if the device_add() return error, the reference
count of the disk object will be reduced twice, at put_device(pdev)
and put_disk(disk). this leads to the end of the object's life cycle
prematurely, and trigger following calltrace.

__init_work+0x2d/0x50 kernel/workqueue.c:519
synchronize_rcu_expedited+0x3af/0x650 kernel/rcu/tree_exp.h:847
bdi_remove_from_list mm/backing-dev.c:938 [inline]
bdi_unregister+0x17f/0x5c0 mm/backing-dev.c:946
release_bdi+0xa1/0xc0 mm/backing-dev.c:968
kref_put include/linux/kref.h:65 [inline]
bdi_put+0x72/0xa0 mm/backing-dev.c:976
bdev_free_inode+0x11e/0x220 block/bdev.c:408
i_callback+0x3f/0x70 fs/inode.c:226
rcu_do_batch kernel/rcu/tree.c:2508 [inline]
rcu_core+0x76d/0x16c0 kernel/rcu/tree.c:2743
__do_softirq+0x1d7/0x93b kernel/softirq.c:558
invoke_softirq kernel/softirq.c:432 [inline]
__irq_exit_rcu kernel/softirq.c:636 [inline]
irq_exit_rcu+0xf2/0x130 kernel/softirq.c:648
sysvec_apic_timer_interrupt+0x93/0xc0

making disk is NULL when calling put_disk().

Reported-by: Hao Sun <[email protected]>
Signed-off-by: Zqiang <[email protected]>
---
v1->v2:
directly returning instead of assigning disk to NULL

block/partitions/core.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/block/partitions/core.c b/block/partitions/core.c
index 3a4898433c43..b9e9af84f518 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -424,6 +424,7 @@ static struct block_device *add_partition(struct gendisk *disk, int partno,
device_del(pdev);
out_put:
put_device(pdev);
+ return ERR_PTR(err);
out_put_disk:
put_disk(disk);
return ERR_PTR(err);
--
2.17.1

2021-10-18 10:36:21

by Christoph Hellwig

Subject: Re: [PATCH v2] block: fix incorrect references to disk objects

Looks good,

Reviewed-by: Christoph Hellwig <[email protected]>

2021-10-18 17:22:10

by Jens Axboe

Subject: Re: [PATCH v2] block: fix incorrect references to disk objects

On Mon, 18 Oct 2021 18:34:22 +0800, Zqiang wrote:
> When adding partitions to the disk, the reference count of the disk
> object is increased. then alloc partition device and called
> device_add(), if the device_add() return error, the reference
> count of the disk object will be reduced twice, at put_device(pdev)
> and put_disk(disk). this leads to the end of the object's life cycle
> prematurely, and trigger following calltrace.
>
> [...]

Applied, thanks!

[1/1] block: fix incorrect references to disk objects
commit: 9fbfabfda25d8774c5a08634fdd2da000a924890

Best regards,
--
Jens Axboe