sctp: validate from_addr_param return

Ilja reported that, simply putting it, nothing was validating that
from_addr_param functions were operating on initialized memory. That is,
the parameter itself was being validated by sctp_walk_params, but it
doesn't check for types and their specific sizes and it could be a 0-length
one, causing from_addr_param to potentially work over the next parameter or
even uninitialized memory.

The fix here is to, in all calls to from_addr_param, check if enough space
is there for the wanted IP address type.

Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 13 deletions

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index 5b44d228b6ca..f33a870b483d 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -2346,11 +2346,13 @@ int sctp_process_init(struct sctp_association *asoc, struct sctp_chunk *chunk,
 
 	/* Process the initialization parameters.  */
 	sctp_walk_params(param, peer_init, init_hdr.params) {
-		if (!src_match && (param.p->type == SCTP_PARAM_IPV4_ADDRESS ||
-		    param.p->type == SCTP_PARAM_IPV6_ADDRESS)) {
+		if (!src_match &&
+		    (param.p->type == SCTP_PARAM_IPV4_ADDRESS ||
+		     param.p->type == SCTP_PARAM_IPV6_ADDRESS)) {
 			af = sctp_get_af_specific(param_type2af(param.p->type));
-			af->from_addr_param(&addr, param.addr,
-					    chunk->sctp_hdr->source, 0);
+			if (!af->from_addr_param(&addr, param.addr,
+						 chunk->sctp_hdr->source, 0))
+				continue;
 			if (sctp_cmp_addr_exact(sctp_source(chunk), &addr))
 				src_match = 1;
 		}
@@ -2531,7 +2533,8 @@ static int sctp_process_param(struct sctp_association *asoc,
 			break;
 do_addr_param:
 		af = sctp_get_af_specific(param_type2af(param.p->type));
-		af->from_addr_param(&addr, param.addr, htons(asoc->peer.port), 0);
+		if (!af->from_addr_param(&addr, param.addr, htons(asoc->peer.port), 0))
+			break;
 		scope = sctp_scope(peer_addr);
 		if (sctp_in_scope(net, &addr, scope))
 			if (!sctp_assoc_add_peer(asoc, &addr, gfp, SCTP_UNCONFIRMED))
@@ -2632,15 +2635,13 @@ do_addr_param:
 		addr_param = param.v + sizeof(struct sctp_addip_param);
 
 		af = sctp_get_af_specific(param_type2af(addr_param->p.type));
-		if (af == NULL)
+		if (!af)
 			break;
 
-		af->from_addr_param(&addr, addr_param,
-				    htons(asoc->peer.port), 0);
+		if (!af->from_addr_param(&addr, addr_param,
+					 htons(asoc->peer.port), 0))
+			break;
 
-		/* if the address is invalid, we can't process it.
-		 * XXX: see spec for what to do.
-		 */
 		if (!af->addr_valid(&addr, NULL, NULL))
 			break;
 
@@ -3054,7 +3055,8 @@ static __be16 sctp_process_asconf_param(struct sctp_association *asoc,
 	if (unlikely(!af))
 		return SCTP_ERROR_DNS_FAILED;
 
-	af->from_addr_param(&addr, addr_param, htons(asoc->peer.port), 0);
+	if (!af->from_addr_param(&addr, addr_param, htons(asoc->peer.port), 0))
+		return SCTP_ERROR_DNS_FAILED;
 
 	/* ADDIP 4.2.1  This parameter MUST NOT contain a broadcast
 	 * or multicast address.
@@ -3331,7 +3333,8 @@ static void sctp_asconf_param_success(struct sctp_association *asoc,
 
 	/* We have checked the packet before, so we do not check again.	*/
 	af = sctp_get_af_specific(param_type2af(addr_param->p.type));
-	af->from_addr_param(&addr, addr_param, htons(bp->port), 0);
+	if (!af->from_addr_param(&addr, addr_param, htons(bp->port), 0))
+		return;
 
 	switch (asconf_param->param_hdr.type) {
 	case SCTP_PARAM_ADD_IP: