sctp: Perform software checksum if packet has to be fragmented.

[ Upstream commit d2dbbba77e95dff4b4f901fee236fef6d9552072 ]

IP/IPv6 fragmentation knows how to compute only TCP/UDP checksum.
This causes problems if SCTP packets has to be fragmented and
ipsummed has been set to PARTIAL due to checksum offload support.
This condition can happen when retransmitting after MTU discover,
or when INIT or other control chunks are larger then MTU.
Check for the rare fragmentation condition in SCTP and use software
checksum calculation in this case.

CC: Fan Du <fan.du@windriver.com>
Signed-off-by: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/sctp/output.c b/net/sctp/output.c
index a1884399c0425bc48424580cf6ac4a82d483ed40..0beb2f9c8a7c6f816a6161d66e44cbd3087dd624 100644 (file)
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -548,7 +548,7 @@ int sctp_packet_transmit(struct sctp_packet *packet)
         */
        if (!sctp_checksum_disable) {
                if (!(dst->dev->features & NETIF_F_SCTP_CSUM) ||
-                   (dst_xfrm(dst) != NULL)) {
+                   (dst_xfrm(dst) != NULL) || packet->ipfragok) {
                        __u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len);
 
                        /* 3) Put the resultant value into the checksum field in the