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

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

On Wed, Jun 14, 2023 at 12:20:39PM +0200, Ulf Hansson wrote:
> On Tue, 13 Jun 2023 at 14:43, Christian Loehle <CLoehle@hyperstone.com> 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>
> 
> Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
> 

All now queued up, thanks.

greg k-h