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SubjectRe: [PATCH] nvme: fix use-after-free during booting
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Hi Christoph,
I modified the patch a bit and now it works.
Best,
- Tong

---
block/genhd.c | 7 +++++--
include/linux/genhd.h | 1 +
2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index 99c64641c314..8c432e5f97ea 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -835,7 +835,10 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk,
* Take an extra ref on queue which will be put on disk_release()
* so that it sticks around as long as @disk is there.
*/
- WARN_ON_ONCE(!blk_get_queue(disk->queue));
+ if (blk_get_queue(disk->queue))
+ disk->flags |= GENHD_FL_QUEUE_REF;
+ else
+ WARN_ON_ONCE(1);

disk_add_events(disk);
blk_integrity_add(disk);
@@ -1567,7 +1570,7 @@ static void disk_release(struct device *dev)
kfree(disk->random);
disk_replace_part_tbl(disk, NULL);
hd_free_part(&disk->part0);
- if (disk->queue)
+ if (disk->flags & GENHD_FL_QUEUE_REF)
blk_put_queue(disk->queue);
kfree(disk);
}
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 4ab853461dff..9441077ee103 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -135,6 +135,7 @@ struct hd_struct {
#define GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE 0x0100
#define GENHD_FL_NO_PART_SCAN 0x0200
#define GENHD_FL_HIDDEN 0x0400
+#define GENHD_FL_QUEUE_REF 0x0800

enum {
DISK_EVENT_MEDIA_CHANGE = 1 << 0, /* media changed */
--
2.25.1

> On Sep 22, 2020, at 12:41 PM, Christoph Hellwig <hch@lst.de> wrote:
>
> On Tue, Sep 22, 2020 at 12:19:06PM -0400, Tong Zhang wrote:
>> Thank you Christoph for providing the patch.
>> However, the test shows that the issue still persists even with the new patch.
>> The call trace is the same as in my first email.
>
> Weird. What baseline did you test? You need to use the patch on top of
> the latest for-next or for-5.10/block tree from Jens for full effect.
>
> If that still feels can you send me a longer dmesg that also shows what
> happens before the sniplet you sent?

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