linux-kernel - Re: [PATCH][next] xsk: Fix null check on error return path

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Message-ID: <20200902162613.GB31464@embeddedor>
Date:   Wed, 2 Sep 2020 11:26:13 -0500
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Björn Töpel <bjorn.topel@...el.com>
Cc:     Magnus Karlsson <magnus.karlsson@...el.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] xsk: Fix null check on error return path

On Wed, Sep 02, 2020 at 05:12:51PM +0200, Björn Töpel wrote:
> On 2020-09-02 17:07, Gustavo A. R. Silva wrote:
> > Currently, dma_map is being checked, when the right object identifier
> > to be null-checked is dma_map->dma_pages, instead.
> > 
> > Fix this by null-checking dma_map->dma_pages.
> > 
> > Addresses-Coverity-ID: 1496811 ("Logically dead code")
> > Fixes: 921b68692abb ("xsk: Enable sharing of dma mappings")
> > Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
> 
> Nice catch!
> 
> Acked-by: Björn Töpel <bjorn.topel@...el.com>
> 

Thanks, Björn.

--
Gustavo

> > ---
> >   net/xdp/xsk_buff_pool.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
> > index 795d7c81c0ca..5b00bc5707f2 100644
> > --- a/net/xdp/xsk_buff_pool.c
> > +++ b/net/xdp/xsk_buff_pool.c
> > @@ -287,7 +287,7 @@ static struct xsk_dma_map *xp_create_dma_map(struct device *dev, struct net_devi
> >   		return NULL;
> >   	dma_map->dma_pages = kvcalloc(nr_pages, sizeof(*dma_map->dma_pages), GFP_KERNEL);
> > -	if (!dma_map) {
> > +	if (!dma_map->dma_pages) {
> >   		kfree(dma_map);
> >   		return NULL;
> >   	}
> >