[PATCH] iommu/mediatek: Fix forever loop in error handling

[Yong Wu (吴勇)]

Hi Joerg,

On Thu, 2022-12-08 at 09:06 +0800, YongWu wrote:
> On Wed, 2022-12-07 at 18:56 +0300, Dan Carpenter wrote:
> > There is a typo so this loop does i++ where i-- was intended.  It
> > will
> > result in looping until the kernel crashes.
> > 
> > Fixes: 26593928564c ("iommu/mediatek: Add error path for loop of
> > mm_dts_parse")
> > Signed-off-by: Dan Carpenter <error27 at gmail.com>
> 
> Sorry for this.
> 
> Reviewed-by: Yong Wu <yong.wu at mediatek.com>
> 
> Thanks Dan.

Could you help apply this?

I reproduced this below issue, and it could be fixed by this patch.

https://lore.kernel.org/linux-mediatek/Y5HrIhEfuEgGKuMB@sirena.org.uk/

Thanks.

> 
> > ---
> >  drivers/iommu/mtk_iommu.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> > index 3e46bc8b0714..2badd6acfb23 100644
> > --- a/drivers/iommu/mtk_iommu.c
> > +++ b/drivers/iommu/mtk_iommu.c
> > @@ -1160,8 +1160,7 @@ static int mtk_iommu_mm_dts_parse(struct
> > device
> > *dev, struct component_match **m
> >  	return 0;
> >  
> >  err_larbdev_put:
> > -	/* id may be not linear mapping, loop whole the array */
> > -	for (i = MTK_LARB_NR_MAX - 1; i >= 0; i++) {
> > +	for (i = MTK_LARB_NR_MAX - 1; i >= 0; i--) {
> >  		if (!data->larb_imu[i].dev)
> >  			continue;
> >  		put_device(data->larb_imu[i].dev);