linux-kernel - Re: [PATCH] staging: greybus: fix fw is NULL but dereferenced

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Date:   Thu, 25 Mar 2021 19:03:39 +0800
From:   Jian Dong <dj0227@....com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     vireshk@...nel.org, johan@...nel.org, elder@...nel.org,
        greybus-dev@...ts.linaro.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org, Jian Dong <dongjian@...ong.com>
Subject: Re: [PATCH]  staging: greybus: fix fw is NULL but dereferenced

On Thu, 25 Mar 2021 11:29:06 +0100
Greg KH <gregkh@...uxfoundation.org> wrote:

> On Thu, Mar 25, 2021 at 06:19:26PM +0800, Jian Dong wrote:
> > From: Jian Dong <dongjian@...ong.com>
> > 
> >  fixes coccicheck Error:
> > 
> >  drivers/staging/greybus/bootrom.c:301:41-45: ERROR:
> >  fw is NULL but dereferenced.
> > 
> >  if procedure goto label directly, ret will be nefative, so the fw
> > is NULL and the if(condition) end with dereferenced fw. let's fix
> > it.  
> 
> Why is this all indented a space?
this maybe caused by my terminal, I will take notice next time.
> 
> > 
> > Signed-off-by: Jian Dong <dongjian@...ong.com>
> > ---
> >  drivers/staging/greybus/bootrom.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/staging/greybus/bootrom.c
> > b/drivers/staging/greybus/bootrom.c index a8efb86..0439efa 100644
> > --- a/drivers/staging/greybus/bootrom.c
> > +++ b/drivers/staging/greybus/bootrom.c
> > @@ -246,7 +246,7 @@ static int gb_bootrom_get_firmware(struct
> > gb_operation *op) struct gb_bootrom_get_firmware_response
> > *firmware_response; struct device *dev =
> > &op->connection->bundle->dev; unsigned int offset, size;
> > -	enum next_request_type next_request;
> > +	enum next_request_type next_request =
> > NEXT_REQ_GET_FIRMWARE; int ret = 0;
> >  
> >  	/* Disable timeouts */
> > @@ -298,10 +298,10 @@ static int gb_bootrom_get_firmware(struct
> > gb_operation *op) 
> >  queue_work:
> >  	/* Refresh timeout */
> > -	if (!ret && (offset + size == fw->size))
> > -		next_request = NEXT_REQ_READY_TO_BOOT;
> > -	else
> > +	if (!!ret)  
> 
> That is hard to understand, please make this more obvious.
> 
if (A && B) else (!A || !B)

So, when ret is NON-ZERO, set next_request as GET_FIRMWARE, else set
READ_TO_BOOT. but if second express is flase, next_request still
need be set as GET_FIRMWARE, So, I initialze it as GET_FIRMWARE.

this is will keep consistent with the origin conditional express:
both ret is ZERO and second express TRUE, then set as READ_TO_BOOT,
else set as GET_FIRMWARE. 
 

> thanks,
> 
> greg k-h