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

[Jesper Dangaard Brouer]

On Tue,  9 Jun 2020 08:08:03 -0400
Gaurav Singh <gaurav1086@xxxxxxxxx> 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@xxxxxxxxx>
> ---
>  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