netdev - Re: [PATCH] bpf: alloc_record_per_cpu Add null check after malloc

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Message-ID: <20200609142315.4d131599@carbon>
Date:   Tue, 9 Jun 2020 14:23:15 +0200
From:   Jesper Dangaard Brouer <jbrouer@...hat.com>
To:     Gaurav Singh <gaurav1086@...il.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        KP Singh <kpsingh@...omium.org>,
        netdev@...r.kernel.org (open list:XDP (eXpress Data Path)),
        bpf@...r.kernel.org (open list:XDP (eXpress Data Path)),
        linux-kernel@...r.kernel.org (open list)
Subject: Re: [PATCH] bpf: alloc_record_per_cpu Add null check after malloc

On Tue,  9 Jun 2020 08:08:03 -0400
Gaurav Singh <gaurav1086@...il.com> wrote:

> The memset call is made right after malloc call. To fix this, add the null check right after malloc and then do memset.
> 

Did you read the section about how long lines should be in desc?


> Signed-off-by: Gaurav Singh <gaurav1086@...il.com>
> ---
>  samples/bpf/xdp_rxq_info_user.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/samples/bpf/xdp_rxq_info_user.c b/samples/bpf/xdp_rxq_info_user.c
> index 4fe47502ebed..490b07b7df78 100644
> --- a/samples/bpf/xdp_rxq_info_user.c
> +++ b/samples/bpf/xdp_rxq_info_user.c
> @@ -202,11 +202,11 @@ static struct datarec *alloc_record_per_cpu(void)
>  
>  	size = sizeof(struct datarec) * nr_cpus;
>  	array = malloc(size);
> -	memset(array, 0, size);
>  	if (!array) {
>  		fprintf(stderr, "Mem alloc error (nr_cpus:%u)\n", nr_cpus);
>  		exit(EXIT_FAIL_MEM);
>  	}
> +	memset(array, 0, size);
>  	return array;
>  }

Looking at code, this bug happen in more places. Please fix up all locations.

I think this fix should go through the "bpf" tree.
Please read:
 https://github.com/torvalds/linux/blob/master/Documentation/bpf/bpf_devel_QA.rst

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer