Messages in this thread | | | Date | Fri, 2 Apr 2021 17:06:25 +0200 | From | Greg KH <> | Subject | Re: [PATCH] drivers core: don't do anything in device_del() when device_add() fail |
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On Thu, Apr 01, 2021 at 09:01:38AM -0400, Yufen Yu wrote: > Recently, our syzbot test reported NULL pointer dereference in > device_del() by injecting memory allocation fail in device_add().
Don't do that :)
> For now, callers of device_add(), such as add_disk(), may ignore > device_add()'s fail and go on working.
Please fix up those users, if device_add() fails there is no need to call device_del().
> In unregister path, it will > call device_del() from del_gendisk(). That can cause various NULL > pointer dereference, including dev->p is NULL in kill_device(), > 'name' is NULL in sysfs_remove_link(), kobj->sd is 'NULL' when call > dpm_sysfs_remove(), and so on. > > To avoid these kernel panic, we call device_del() only when device_add() > is success.
As Rafael said, that's not what you are doing here, so even if I wanted to take this patch, I can't.
> > Signed-off-by: Yufen Yu <yuyufen@huawei.com> > --- > drivers/base/core.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index f29839382f81..a10ec5dbc577 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -3380,6 +3380,9 @@ void device_del(struct device *dev) > struct class_interface *class_intf; > unsigned int noio_flag; > > + if (!dev->p) > + return;
Also, this isn't a good test as it's not obvious what you are trying to check for here.
thanks,
greg k-h
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