Re: [PATCH] amba: fix refcount underflow if amba_device_add() fails

[Kefeng Wang]

On 2022/5/24 11:09, Guenter Roeck wrote:
> On Tue, May 24, 2022 at 10:51:39AM +0800, Kefeng Wang wrote:
> > "ARM: 9192/1: amba: fix memory leak in amba_device_try_add()" leads
> > to a refcount underflow if amba_device_add() fails, which called by
> > of_amba_device_create(), the of_amba_device_create() already exists
> > the error handling, so amba_put_device() only need to be added into
> > amba_deferred_retry().
> >
> > Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> > Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>

Thanks.

PS: I also test with kmemleak, this could also fix previous memory leak 
issue.

> Thanks,
> Guenter
>
> > ---
> >   drivers/amba/bus.c | 8 ++------
> >   1 file changed, 2 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> > index 0e3ed5eb367b..0cb20324da16 100644
> > --- a/drivers/amba/bus.c
> > +++ b/drivers/amba/bus.c
> > @@ -493,13 +493,8 @@ static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
> >   		goto skip_probe;
> >   
> >   	ret = amba_read_periphid(dev);
> > -	if (ret) {
> > -		if (ret != -EPROBE_DEFER) {
> > -			amba_device_put(dev);
> > -			goto err_out;
> > -		}
> > +	if (ret)
> >   		goto err_release;
> > -	}
> >   
> >   skip_probe:
> >   	ret = device_add(&dev->dev);
> > @@ -546,6 +541,7 @@ static int amba_deferred_retry(void)
> >   			continue;
> >   
> >   		list_del_init(&ddev->node);
> > +		amba_device_put(ddev->dev);
> >   		kfree(ddev);
> >   	}
> >   
> > --
> > 2.35.3
> .