netdev - Re: [PATCH v2] net: bridge: add compile-time assert for cb struct size

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 03 Mar 2015 15:28:47 +0100
From:	Daniel Borkmann <daniel@...earbox.net>
To:	David Laight <David.Laight@...LAB.COM>,
	'Florian Westphal' <fw@...len.de>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH v2] net: bridge: add compile-time assert for cb struct
 size

On 03/03/2015 02:50 PM, David Laight wrote:
...
>> +	BUILD_BUG_ON(sizeof(struct br_input_skb_cb) > FIELD_SIZEOF(struct sk_buff, cb));
>> +
>
> What about using something based on:
> #define GET_CB(skb, type) ((type *)((skb)->cb + (sizeof (char[(sizeof (type) <= sizeof (skb->cb)) ? 1 : -1] - 1)))
> to access skb->sb?

That would require to change all skb->cb[] call-sites everywhere.

Besides that, this macro is also buggy, my totally untrained lisp-eye tells
me that you got your brackets wrong.

Cheers,
Daniel
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html