linux-kernel - RE: [PATCH v3 5/6] staging: r8188eu: add error handling of rtw

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Date:   Thu, 26 Aug 2021 10:59:14 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Pavel Skripkin' <paskripkin@...il.com>
CC:     "Larry.Finger@...inger.net" <Larry.Finger@...inger.net>,
        "phil@...lpotter.co.uk" <phil@...lpotter.co.uk>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "straube.linux@...il.com" <straube.linux@...il.com>,
        "fmdefrancesco@...il.com" <fmdefrancesco@...il.com>,
        "linux-staging@...ts.linux.dev" <linux-staging@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3 5/6] staging: r8188eu: add error handling of rtw_read32

From: Pavel Skripkin
> Sent: 26 August 2021 11:55
> 
> On 8/26/21 1:22 PM, David Laight wrote:
> > From: Pavel Skripkin
> >> Sent: 26 August 2021 10:28
> >>
> >> On 8/26/21 12:22 PM, Pavel Skripkin wrote:
> >> > On Thu, 26 Aug 2021 08:51:23 +0000
> >> > David Laight <David.Laight@...LAB.COM> wrote:
> > ...
> >> >> ...
> >> >> > -static u32 usb_read32(struct intf_hdl *pintfhdl, u32 addr)
> >> >> > +static int usb_read32(struct intf_hdl *pintfhdl, u32 addr, u32
> >> >> > *data) {
> >> >> >  	u8 requesttype;
> >> >> >  	u16 wvalue;
> >> >> >  	u16 len;
> >> >> > -	__le32 data;
> >> >> > +	int res;
> >> >> > +	__le32 tmp;
> >> >> > +
> >> >> > +	if (WARN_ON(unlikely(!data)))
> >> >> > +		return -EINVAL;
> >> >> >
> >> >>
> >> >> Kill the NULL check - it is a silly coding error.
> >> >> An OOPS is just as easy to debug.
> >> >>
> >> >
> >> >
> >> > I don't think that one single driver should kill the whole system. It's
> >> > 100% an error, but kernel can recover from it (for example disconnect
> >> > the driver, since it's broken).
> >> >
> >> >
> >> > AFIAK, Greg and Linus do not like BUG_ONs in recoverable state...
> >> > Correct me, if I am wrong
> >> >
> >> Oops, I thought about BUG_ON() instead of WARN_ON(), sorry for
> >> confusion. My point is "we should not let the box boom".
> >
> >
> > There is no point checking for NULL that just can't happen.
> > In this case all the callers will pass the address of a local.
> > There really is no point checking.
> >
> 
> We not always read in local variable, there are few places, where we
> read into passed buffer.

It is still a very local coding bug.

	David

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