Patchwork [18/18] sctp: Correct type and usage of sctp_end_cksum()

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Submitter Pablo Neira
Date April 29, 2013, 6:22 p.m.
Message ID <>
Download mbox | patch
Permalink /patch/240439/
State Accepted
Headers show


Pablo Neira - April 29, 2013, 6:22 p.m.
From: Simon Horman <>

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.


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 <>
Signed-off-by: Pablo Neira Ayuso <>
 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 = sctp_end_cksum(crc32);
-	hdr->checksum = crc32;
+	hdr->checksum = sctp_end_cksum(crc32);
 	return true;