netdev - Re: [PATCH 1/3] cw1200: Don't leak memory if krealloc failes

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Date:   Fri, 30 Sep 2016 15:00:32 +0200
From:   Johannes Thumshirn <jthumshirn@...e.de>
To:     Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
Cc:     Solomon Peachy <pizza@...ftnet.org>,
        Kalle Valo <kvalo@...eaurora.org>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] cw1200: Don't leak memory if krealloc failes

On Fri, Sep 30, 2016 at 03:56:45PM +0300, Sergei Shtylyov wrote:
> Hello.
> 
> On 9/30/2016 3:11 PM, Johannes Thumshirn wrote:
> 
> > The call to krealloc() in wsm_buf_reserve() directly assigns the newly
> > returned memory to buf->begin. This is all fine except when krealloc()
> > failes we loose the ability to free the old memory pointed to by
> 
>    Fails.
> 
> > buf->begin. If we just create a temporary variable to assign memory to
> > and assign the memory to it we can mitigate the memory leak.
> > 
> > Signed-off-by: Johannes Thumshirn <jthumshirn@...e.de>
> > ---
> >  drivers/net/wireless/st/cw1200/wsm.c | 16 +++++++++-------
> >  1 file changed, 9 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/net/wireless/st/cw1200/wsm.c b/drivers/net/wireless/st/cw1200/wsm.c
> > index 680d60e..12fad99 100644
> > --- a/drivers/net/wireless/st/cw1200/wsm.c
> > +++ b/drivers/net/wireless/st/cw1200/wsm.c
> > @@ -1807,16 +1807,18 @@ static int wsm_buf_reserve(struct wsm_buf *buf, size_t extra_size)
> >  {
> >  	size_t pos = buf->data - buf->begin;
> >  	size_t size = pos + extra_size;
> > +	u8 *tmp;
> > 
> >  	size = round_up(size, FWLOAD_BLOCK_SIZE);
> > 
> > -	buf->begin = krealloc(buf->begin, size, GFP_KERNEL | GFP_DMA);
> > -	if (buf->begin) {
> > -		buf->data = &buf->begin[pos];
> > -		buf->end = &buf->begin[size];
> > -		return 0;
> > -	} else {
> > -		buf->end = buf->data = buf->begin;
> > +	tmp = krealloc(buf->begin, size, GFP_KERNEL | GFP_DMA);
> > +	if (tmp) {
> 
>    !tmp, you mean?

Yes, I've already sent out a v2.

-- 
Johannes Thumshirn                                          Storage
jthumshirn@...e.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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