ipv6: rpl: fix loop iteration

This patch fix the loop iteration by not walking over the last
iteration. The cmpri compressing value exempt the last segment. As the
code shows the last iteration will be overwritten by cmpre value
handling which is for the last segment.

I think this doesn't end in any bufferoverflows because we work on worst
case temporary buffer sizes but it ends in not best compression settings
in some cases.

Fixes: 8610c7c ("net: ipv6: add support for rpl sr exthdr")
Signed-off-by: Alexander Aring <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: alexaring

net/ipv6/rpl.c

@@ -48,7 +48,7 @@ void ipv6_rpl_srh_decompress(struct ipv6_rpl_sr_hdr *outhdr,
 	outhdr->cmpri = 0;
 	outhdr->cmpre = 0;
 
-	for (i = 0; i <= n; i++)
+	for (i = 0; i < n; i++)
 		ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[i], daddr,
 					 ipv6_rpl_segdata_pos(inhdr, i),
 					 inhdr->cmpri);
@@ -66,7 +66,7 @@ static unsigned char ipv6_rpl_srh_calc_cmpri(const struct ipv6_rpl_sr_hdr *inhdr
 	int i;
 
 	for (plen = 0; plen < sizeof(*daddr); plen++) {
-		for (i = 0; i <= n; i++) {
+		for (i = 0; i < n; i++) {
 			if (daddr->s6_addr[plen] !=
 			    inhdr->rpl_segaddr[i].s6_addr[plen])
 				return plen;
@@ -114,7 +114,7 @@ void ipv6_rpl_srh_compress(struct ipv6_rpl_sr_hdr *outhdr,
 	outhdr->cmpri = cmpri;
 	outhdr->cmpre = cmpre;
 
-	for (i = 0; i <= n; i++)
+	for (i = 0; i < n; i++)
 		ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, i),
 				       &inhdr->rpl_segaddr[i], cmpri);