* [PATCH] block: Do not call blk_put_queue() if gendisk allocation fails
@ 2022-08-11 23:23 Rafael Mendonca
2022-08-12 5:42 ` Christoph Hellwig
2022-08-12 12:42 ` Jens Axboe
0 siblings, 2 replies; 3+ messages in thread
From: Rafael Mendonca @ 2022-08-11 23:23 UTC (permalink / raw)
To: Jens Axboe, Hannes Reinecke
Cc: Rafael Mendonca, syzbot+31c9594f6e43b9289b25, Hillf Danton,
linux-block, linux-kernel
Commit 6f8191fdf41d ("block: simplify disk shutdown") removed the call
to blk_get_queue() during gendisk allocation but missed to remove the
corresponding cleanup code blk_put_queue() for it. Thus, if the gendisk
allocation fails, the request_queue refcount gets decremented and
reaches 0, causing blk_mq_release() to be called with a hctx still
alive. That triggers a WARNING report, as found by syzkaller:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 23016 at block/blk-mq.c:3881
blk_mq_release+0xf8/0x3e0 block/blk-mq.c:3881
[...] stripped
RIP: 0010:blk_mq_release+0xf8/0x3e0 block/blk-mq.c:3881
[...] stripped
Call Trace:
<TASK>
blk_release_queue+0x153/0x270 block/blk-sysfs.c:780
kobject_cleanup lib/kobject.c:673 [inline]
kobject_release lib/kobject.c:704 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x1c8/0x540 lib/kobject.c:721
__alloc_disk_node+0x4f7/0x610 block/genhd.c:1388
__blk_mq_alloc_disk+0x13b/0x1f0 block/blk-mq.c:3961
loop_add+0x3e2/0xaf0 drivers/block/loop.c:1978
loop_control_ioctl+0x133/0x620 drivers/block/loop.c:2150
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
[...] stripped
Fixes: 6f8191fdf41d ("block: simplify disk shutdown")
Reported-by: syzbot+31c9594f6e43b9289b25@syzkaller.appspotmail.com
Suggested-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Rafael Mendonca <rafaelmendsr@gmail.com>
---
block/genhd.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/block/genhd.c b/block/genhd.c
index b901fea1d55a..d36fabf0abc1 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1341,7 +1341,7 @@ struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id,
disk = kzalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);
if (!disk)
- goto out_put_queue;
+ return NULL;
if (bioset_init(&disk->bio_split, BIO_POOL_SIZE, 0, 0))
goto out_free_disk;
@@ -1390,8 +1390,6 @@ struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id,
bioset_exit(&disk->bio_split);
out_free_disk:
kfree(disk);
-out_put_queue:
- blk_put_queue(q);
return NULL;
}
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] block: Do not call blk_put_queue() if gendisk allocation fails
2022-08-11 23:23 [PATCH] block: Do not call blk_put_queue() if gendisk allocation fails Rafael Mendonca
@ 2022-08-12 5:42 ` Christoph Hellwig
2022-08-12 12:42 ` Jens Axboe
1 sibling, 0 replies; 3+ messages in thread
From: Christoph Hellwig @ 2022-08-12 5:42 UTC (permalink / raw)
To: Rafael Mendonca
Cc: Jens Axboe, Hannes Reinecke, syzbot+31c9594f6e43b9289b25,
Hillf Danton, linux-block, linux-kernel
Looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] block: Do not call blk_put_queue() if gendisk allocation fails
2022-08-11 23:23 [PATCH] block: Do not call blk_put_queue() if gendisk allocation fails Rafael Mendonca
2022-08-12 5:42 ` Christoph Hellwig
@ 2022-08-12 12:42 ` Jens Axboe
1 sibling, 0 replies; 3+ messages in thread
From: Jens Axboe @ 2022-08-12 12:42 UTC (permalink / raw)
To: rafaelmendsr, hare
Cc: linux-block, hdanton, linux-kernel, syzbot+31c9594f6e43b9289b25
On Thu, 11 Aug 2022 20:23:37 -0300, Rafael Mendonca wrote:
> Commit 6f8191fdf41d ("block: simplify disk shutdown") removed the call
> to blk_get_queue() during gendisk allocation but missed to remove the
> corresponding cleanup code blk_put_queue() for it. Thus, if the gendisk
> allocation fails, the request_queue refcount gets decremented and
> reaches 0, causing blk_mq_release() to be called with a hctx still
> alive. That triggers a WARNING report, as found by syzkaller:
>
> [...]
Applied, thanks!
[1/1] block: Do not call blk_put_queue() if gendisk allocation fails
commit: aa0c680c3aa96a5f9f160d90dd95402ad578e2b0
Best regards,
--
Jens Axboe
^ permalink raw reply [flat|nested] 3+ messages in thread
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Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2022-08-11 23:23 [PATCH] block: Do not call blk_put_queue() if gendisk allocation fails Rafael Mendonca
2022-08-12 5:42 ` Christoph Hellwig
2022-08-12 12:42 ` Jens Axboe
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