[PATCH] nvme: fix use-after-free during booting

[Tong Zhang]

Thank you Christoph.
I will do some testing with my setup and let you know.
- Tong

On Tue, Sep 22, 2020 at 9:59 AM Christoph Hellwig <hch at lst.de> wrote:
>
> Hi Tong,
>
> can you test this patch?
>
> diff --git a/block/genhd.c b/block/genhd.c
> index 99c64641c3148c..6473ae703789e4 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -836,6 +836,7 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk,
>          * so that it sticks around as long as @disk is there.
>          */
>         WARN_ON_ONCE(!blk_get_queue(disk->queue));
> +       disk->flags |= GENHD_FL_QUEUE_REF;
>
>         disk_add_events(disk);
>         blk_integrity_add(disk);
> @@ -1567,7 +1568,7 @@ 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 4ab853461dff25..9441077ee10329 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 */