Re: [PATCH] bcache: fix uninitialized closure object

["Coly Li" <colyli@fnnas.com>]

On Thu, Apr 02, 2026 at 09:03:53PM +0800, mingzhe.zou@easystack.cn wrote:
> From: Mingzhe Zou <zoumingzhe@qq.com>
> 
> In the previous patch(bcache: fix cached_dev.sb_bio use-after-free and crash),
> we adopted a simple modification suggestion from AI to fix the use-after-free.
> 
> But in actual testing, we found an extreme case where the device is stopped
> before calling bch_write_bdev_super().
> 
> At this point, struct closure sb_write has not been initialized yet.
> 
> For this patch, we ensure that sb_bio has been completed via sb_write_mutex.
> 
> Signed-off-by: Mingzhe Zou <mingzhe.zou@easystack.cn>

It looks good to me. I will refine the commit log and submit.

Thanks.

Coly Li

> ---
>  drivers/md/bcache/super.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index 6627a381f65a..97d9adb0bf96 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -1378,7 +1378,8 @@ static CLOSURE_CALLBACK(cached_dev_free)
>  	 * The sb_bio is embedded in struct cached_dev, so we must
>  	 * ensure no I/O is in progress.
>  	 */
> -	closure_sync(&dc->sb_write);
> +	down(&dc->sb_write_mutex);
> +	up(&dc->sb_write_mutex);
>  
>  	if (dc->sb_disk)
>  		folio_put(virt_to_folio(dc->sb_disk));
> -- 
> 2.34.1