netdev - Re: [PATCHv3 net-next 4/4] sctp: implement sender-side procedures for Add Incoming/Outgoing Streams Request Parameter

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Message-ID: <20170123184744.GC3781@localhost.localdomain>
Date:   Mon, 23 Jan 2017 16:47:44 -0200
From:   Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:     David Laight <David.Laight@...LAB.COM>
Cc:     "'Xin Long'" <lucien.xin@...il.com>,
        network dev <netdev@...r.kernel.org>,
        "linux-sctp@...r.kernel.org" <linux-sctp@...r.kernel.org>,
        Neil Horman <nhorman@...driver.com>,
        Vlad Yasevich <vyasevich@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>
Subject: Re: [PATCHv3 net-next 4/4] sctp: implement sender-side procedures
 for Add Incoming/Outgoing Streams Request Parameter

On Mon, Jan 23, 2017 at 11:25:56AM +0000, David Laight wrote:
> From: Xin Long
> > Sent: 19 January 2017 17:19
> > This patch is to implement Sender-Side Procedures for the Add
> > Outgoing and Incoming Streams Request Parameter described in
> > rfc6525 section 5.1.5-5.1.6.
> > 
> > It is also to add sockopt SCTP_ADD_STREAMS in rfc6525 section
> > 6.3.4 for users.
> ...
> > +	out = params->sas_outstrms;
> > +	in  = params->sas_instrms;
> > +
> > +	if (!out && !in)
> > +		goto out;
> > +
> > +	if (out) {
> > +		__u16 nums = stream->outcnt + out;
> 
> Make nums 'unsigned int', the code will be smaller and you can
> use the value for the overflow check.

Smaller as in to avoid the sum below?

> 
> > +		/* Check for overflow, can't use nums here */
> > +		if (stream->outcnt + out > SCTP_MAX_STREAM)
> > +			goto out;
> > +
> > +		/* Use ksize to check if stream array really needs to realloc */
> > +		if (ksize(stream->out) / sizeof(*stream->out) < nums) {
> > +			struct sctp_stream_out *streamout;
> > +
> > +			streamout = kcalloc(nums, sizeof(*streamout),
> > +					    GFP_KERNEL);
> > +			if (!streamout) {
> > +				retval = -ENOMEM;
> > +				goto out;
> > +			}
> > +
> > +			memcpy(streamout, stream->out,
> > +			       sizeof(*streamout) * stream->outcnt);
> > +
> > +			kfree(stream->out);
> > +			stream->out = streamout;
> > +		}
> 
> Does kcalloc() zero the entire area, or just the length you ask for?
> If the latter you need to zero the rest here.
> ...
> 
> 	David
> 
> --
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