Subject: Re: [PATCH] sctp: Correct type and usage of sctp_end_cksum()

From: Pablo Neira Ayuso <[email-masked]>
Date: Thu, 25 Apr 2013 16:35:39 +0200

On Thu, Apr 25, 2013 at 10:12:14PM +0900, Simon Horman wrote:
> On Fri, Apr 19, 2013 at 09:10:43AM -0400, Neil Horman wrote:
> > On Fri, Apr 19, 2013 at 10:54:58AM +0900, Simon Horman wrote:
> > > Change the type of the crc32 parameter of sctp_end_cksum()
> > > from __be32 to __u32 to reflect that fact that it is passed
> > > to cpu_to_le32().
> > > 
> > > There are five in-tree users of sctp_end_cksum().
> > > The following four had warnings flagged by sparse which are
> > > no longer present with this change.
> > > 
> > > net/netfilter/ipvs/ip_vs_proto_sctp.c:sctp_nat_csum()
> > > net/netfilter/ipvs/ip_vs_proto_sctp.c:sctp_csum_check()
> > > net/sctp/input.c:sctp_rcv_checksum()
> > > net/sctp/output.c:sctp_packet_transmit()
> > > 
> > > The fifth user is net/netfilter/nf_nat_proto_sctp.c:sctp_manip_pkt().
> > > It has been updated to pass a __u32 instead of a __be32,
> > > the value in question was already calculated in cpu byte-order.
> > > 
> > > net/netfilter/nf_nat_proto_sctp.c:sctp_manip_pkt() has also
> > > been updated to assign the return value of sctp_end_cksum()
> > > directly to a variable of type __le32, matching the
> > > type of the return value. Previously the return value
> > > was assigned to a variable of type __be32 and then that variable
> > > was finally assigned to another variable of type __le32.
> > > 
> > > Problems flagged by sparse.
> > > Compile and sparse tested only.
> > > 
> > > Signed-off-by: Simon Horman <[email-masked]>
> > > ---
> > >  include/net/sctp/checksum.h       |    2 +-
> > >  net/netfilter/nf_nat_proto_sctp.c |    5 ++---
> > >  2 files changed, 3 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/include/net/sctp/checksum.h b/include/net/sctp/checksum.h
> > > index befc8d2..5a2110d 100644
> > > --- a/include/net/sctp/checksum.h
> > > +++ b/include/net/sctp/checksum.h
> > > @@ -77,7 +77,7 @@ static inline __u32 sctp_update_cksum(__u8 *buffer, __u16 length, __u32 crc32)
> > >  	return sctp_crc32c(crc32, buffer, length);
> > >  }
> > >  
> > > -static inline __le32 sctp_end_cksum(__be32 crc32)
> > > +static inline __le32 sctp_end_cksum(__u32 crc32)
> > >  {
> > >  	return cpu_to_le32(~crc32);
> > >  }
> > > diff --git a/net/netfilter/nf_nat_proto_sctp.c b/net/netfilter/nf_nat_proto_sctp.c
> > > index e64faa5..396e55d 100644
> > > --- a/net/netfilter/nf_nat_proto_sctp.c
> > > +++ b/net/netfilter/nf_nat_proto_sctp.c
> > > @@ -36,7 +36,7 @@ sctp_manip_pkt(struct sk_buff *skb,
> > >  {
> > >  	struct sk_buff *frag;
> > >  	sctp_sctphdr_t *hdr;
> > > -	__be32 crc32;
> > > +	__u32 crc32;
> > >  
> > >  	if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
> > >  		return false;
> > > @@ -55,8 +55,7 @@ sctp_manip_pkt(struct sk_buff *skb,
> > >  	skb_walk_frags(skb, frag)
> > >  		crc32 = sctp_update_cksum((u8 *)frag->data, skb_headlen(frag),
> > >  					  crc32);
> > > -	crc32 = sctp_end_cksum(crc32);
> > > -	hdr->checksum = crc32;
> > > +	hdr->checksum = sctp_end_cksum(crc32);
> > >  
> > >  	return true;
> > >  }
> > > -- 
> > > 1.7.10.4
> > > 
> > > 
> > Acked-by: Neil Horman <[email-masked]>
> 
> Pablo, are you interested in taking this through nf-next?

I'll take it. Let's see if we still reach the merge window open yet.