From: Marek Vasut <marex@denx.de>
To: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: "Marc Kleine-Budde" <mkl@pengutronix.de>,
linux-can@vger.kernel.org,
Wolfgang Grandegger <wg@grandegger.com>,
netdev@vger.kernel.org
Subject: Re: [PATCH] can: Use correct type in sizeof() in nla_put()
Date: Fri, 30 Oct 2015 16:33:11 +0100 [thread overview]
Message-ID: <201510301633.11762.marex@denx.de> (raw)
In-Reply-To: <5633846B.30107@hartkopp.net>
On Friday, October 30, 2015 at 03:53:31 PM, Oliver Hartkopp wrote:
> On 10/30/2015 03:24 PM, Marek Vasut wrote:
> > On Friday, October 30, 2015 at 03:17:44 PM, Marc Kleine-Budde wrote:
> >> On 10/30/2015 03:01 PM, Marek Vasut wrote:
> >>> Are you absolutelly positive this doesn't break kernel ABI please ?
> >>>
> >>> I am a little worried there, since the size of can_clock and
> >>> can_ctrlmode structures differ.
> >>
> >> struct can_clock is a u32, see [1]
> >> struct can_ctrlmode is 2 x u32.
> >>
> >> in libsocketcan[2] it's accessed like this:
> >>> memcpy(res,
> >>>
> >>> RTA_DATA(can_attr[IFLA_CAN_CLOCK]),
> >>> sizeof(struct can_clock));
> >>
> >> I think it should be ok.
> >
> > In that case, yes, it's good. Hopefully, noone wrote his own thing.
>
> Fortunately ip from iproute2 does it similary:
>
> https://git.kernel.org/cgit/linux/kernel/git/shemminger/iproute2.git/tree/i
> p/iplink_can.c#n338
>
>
> if (tb[IFLA_CAN_CLOCK]) {
> struct can_clock *clock = RTA_DATA(tb[IFLA_CAN_CLOCK]);
>
> fprintf(f, "\n clock %d", clock->freq);
> }
>
> As the clock is a read-only value kernel->userspace and nla_put creates its
> own small ID/length information each time we are REALLY LUCKY that this fix
> doesn't break the ABI in this case.
>
> When can_clock would have been greater then can_ctrlmode we really had a
> problem ...
>
> Thanks for caching this!
Yeah, I already had one leg in my asbestos trousers all right. Thanks for
double-checking this!
Best regards,
Marek Vasut
next prev parent reply other threads:[~2015-10-30 15:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-30 12:48 [PATCH] can: Use correct type in sizeof() in nla_put() Marek Vasut
2015-10-30 13:40 ` Marc Kleine-Budde
2015-10-30 14:01 ` Marek Vasut
2015-10-30 14:17 ` Marc Kleine-Budde
2015-10-30 14:24 ` Marek Vasut
2015-10-30 14:53 ` Oliver Hartkopp
2015-10-30 15:33 ` Marek Vasut [this message]
2015-10-30 13:39 pull-request: can 2015-10-30 Marc Kleine-Budde
2015-10-30 13:39 ` [PATCH] can: Use correct type in sizeof() in nla_put() Marc Kleine-Budde
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=201510301633.11762.marex@denx.de \
--to=marex@denx.de \
--cc=linux-can@vger.kernel.org \
--cc=mkl@pengutronix.de \
--cc=netdev@vger.kernel.org \
--cc=socketcan@hartkopp.net \
--cc=wg@grandegger.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).