netdev - RE: [PATCH 20/39] netfilter: ipset: Use kmalloc() in comment extension helper

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Date:   Tue, 15 Nov 2016 10:48:33 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Pablo Neira Ayuso' <pablo@...filter.org>,
        "netfilter-devel@...r.kernel.org" <netfilter-devel@...r.kernel.org>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH 20/39] netfilter: ipset: Use kmalloc() in comment
 extension helper

From: Pablo Neira Ayuso
> Sent: 13 November 2016 22:25
> Allocate memory with kmalloc() rather than kzalloc(): the string
> is immediately initialized so it is unnecessary to zero out
> the allocated memory area.
> 
> Ported from a patch proposed by Sergey Popovich <popovich_sergei@...l.ua>.
> 
> Suggested-by: Sergey Popovich <popovich_sergei@...l.ua>
> Signed-off-by: Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>
> ---
>  include/linux/netfilter/ipset/ip_set_comment.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/netfilter/ipset/ip_set_comment.h
> b/include/linux/netfilter/ipset/ip_set_comment.h
> index bae5c7609be2..5444b1bbe656 100644
> --- a/include/linux/netfilter/ipset/ip_set_comment.h
> +++ b/include/linux/netfilter/ipset/ip_set_comment.h
> @@ -34,7 +34,7 @@ ip_set_init_comment(struct ip_set_comment *comment,
>  		return;
>  	if (unlikely(len > IPSET_MAX_COMMENT_SIZE))
>  		len = IPSET_MAX_COMMENT_SIZE;
> -	c = kzalloc(sizeof(*c) + len + 1, GFP_ATOMIC);
> +	c = kmalloc(sizeof(*c) + len + 1, GFP_ATOMIC);
>  	if (unlikely(!c))
>  		return;
>  	strlcpy(c->str, ext->comment, len + 1);

I think I'd do a memcpy() and zero the last byte.

Note that any other parts of 'c->' are no longer zeroed by this code fragment.

	David