Re: [PATCH] mmc: block: ensure error propagation for non-blk

["gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>]

On Mon, Jun 05, 2023 at 01:46:16PM +0000, Christian Loehle wrote:
> commit 003fb0a51162d940f25fc35e70b0996a12c9e08a upstream.
> 
> Requests to the mmc layer usually come through a block device IO.
> The exceptions are the ioctl interface, RPMB chardev ioctl
> and debugfs, which issue their own blk_mq requests through
> blk_execute_rq and do not query the BLK_STS error but the
> mmcblk-internal drv_op_result. This patch ensures that drv_op_result
> defaults to an error and has to be overwritten by the operation
> to be considered successful.
> 
> The behavior leads to a bug where the request never propagates
> the error, e.g. by directly erroring out at mmc_blk_mq_issue_rq if
> mmc_blk_part_switch fails. The ioctl caller of the rpmb chardev then
> can never see an error (BLK_STS_IOERR, but drv_op_result is unchanged)
> and thus may assume that their call executed successfully when it did not.
> 
> While always checking the blk_execute_rq return value would be
> advised, let's eliminate the error by always setting
> drv_op_result as -EIO to be overwritten on success (or other error)
> 
> Fixes: 614f0388f580 ("mmc: block: move single ioctl() commands to block requests")
> Signed-off-by: Christian Loehle <cloehle@hyperstone.com>
> ---
>  drivers/mmc/core/block.c | 5 +++++
>  1 file changed, 5 insertions(+)

What stable tree(s) do you want this applied to?

thanks,

greg k-h