Merge branch 'sctp-nested-flex-arrays'

Xin Long says:

====================
sctp: fix a plenty of flexible-array-nested warnings

Paolo noticed a compile warning in SCTP,

../net/sctp/stream_sched_fc.c: note: in included file (through ../include/net/sctp/sctp.h):
../include/net/sctp/structs.h:335:41: warning: array of flexible structures

But not only this, there are actually quite a lot of such warnings in
some SCTP structs. This patchset fixes most of warnings by deleting
these nested flexible array members.

After this patchset, there are still some warnings left:

  # make C=2 CF="-Wflexible-array-nested" M=./net/sctp/
  ./include/net/sctp/structs.h:1145:41: warning: nested flexible array
  ./include/uapi/linux/sctp.h:641:34: warning: nested flexible array
  ./include/uapi/linux/sctp.h:643:34: warning: nested flexible array
  ./include/uapi/linux/sctp.h:644:33: warning: nested flexible array
  ./include/uapi/linux/sctp.h:650:40: warning: nested flexible array
  ./include/uapi/linux/sctp.h:653:39: warning: nested flexible array

the 1st is caused by __data[] in struct ip_options, not in SCTP;
the others are in uapi, and we should not touch them.

Note that instead of completely deleting it, we just leave it as a
comment in the struct, signalling to the reader that we do expect
such variable parameters over there, as Marcelo suggested.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

Author: davem330

include/linux/sctp.h

@@ -222,7 +222,7 @@ struct sctp_datahdr {
 	__be16 stream;
 	__be16 ssn;
 	__u32 ppid;
-	__u8  payload[];
+	/* __u8  payload[]; */
 };
 
 struct sctp_data_chunk {
@@ -270,7 +270,7 @@ struct sctp_inithdr {
 	__be16 num_outbound_streams;
 	__be16 num_inbound_streams;
 	__be32 initial_tsn;
-	__u8  params[];
+	/* __u8  params[]; */
 };
 
 struct sctp_init_chunk {
@@ -385,7 +385,7 @@ struct sctp_sackhdr {
 	__be32 a_rwnd;
 	__be16 num_gap_ack_blocks;
 	__be16 num_dup_tsns;
-	union sctp_sack_variable variable[];
+	/* union sctp_sack_variable variable[]; */
 };
 
 struct sctp_sack_chunk {
@@ -443,7 +443,7 @@ struct sctp_shutdown_chunk {
 struct sctp_errhdr {
 	__be16 cause;
 	__be16 length;
-	__u8  variable[];
+	/* __u8  variable[]; */
 };
 
 struct sctp_operr_chunk {
@@ -603,7 +603,7 @@ struct sctp_fwdtsn_skip {
 
 struct sctp_fwdtsn_hdr {
 	__be32 new_cum_tsn;
-	struct sctp_fwdtsn_skip skip[];
+	/* struct sctp_fwdtsn_skip skip[]; */
 };
 
 struct sctp_fwdtsn_chunk {
@@ -620,7 +620,7 @@ struct sctp_ifwdtsn_skip {
 
 struct sctp_ifwdtsn_hdr {
 	__be32 new_cum_tsn;
-	struct sctp_ifwdtsn_skip skip[];
+	/* struct sctp_ifwdtsn_skip skip[]; */
 };
 
 struct sctp_ifwdtsn_chunk {
@@ -667,7 +667,7 @@ struct sctp_addip_param {
 
 struct sctp_addiphdr {
 	__be32	serial;
-	__u8	params[];
+	/* __u8	params[]; */
 };
 
 struct sctp_addip_chunk {
@@ -727,7 +727,7 @@ struct sctp_addip_chunk {
 struct sctp_authhdr {
 	__be16 shkey_id;
 	__be16 hmac_id;
-	__u8   hmac[];
+	/* __u8   hmac[]; */
 };
 
 struct sctp_auth_chunk {
@@ -742,7 +742,7 @@ struct sctp_infox {
 
 struct sctp_reconf_chunk {
 	struct sctp_chunkhdr chunk_hdr;
-	__u8 params[];
+	/* __u8 params[]; */
 };
 
 struct sctp_strreset_outreq {

include/net/sctp/sctp.h

@@ -425,11 +425,11 @@ static inline bool sctp_chunk_pending(const struct sctp_chunk *chunk)
  * the chunk length to indicate when to stop.  Make sure
  * there is room for a param header too.
  */
-#define sctp_walk_params(pos, chunk, member)\
-_sctp_walk_params((pos), (chunk), ntohs((chunk)->chunk_hdr.length), member)
+#define sctp_walk_params(pos, chunk)\
+_sctp_walk_params((pos), (chunk), ntohs((chunk)->chunk_hdr.length))
 
-#define _sctp_walk_params(pos, chunk, end, member)\
-for (pos.v = chunk->member;\
+#define _sctp_walk_params(pos, chunk, end)\
+for (pos.v = (u8 *)(chunk + 1);\
      (pos.v + offsetof(struct sctp_paramhdr, length) + sizeof(pos.p->length) <=\
       (void *)chunk + end) &&\
      pos.v <= (void *)chunk + end - ntohs(pos.p->length) &&\
@@ -452,8 +452,8 @@ for (err = (struct sctp_errhdr *)((void *)chunk_hdr + \
 _sctp_walk_fwdtsn((pos), (chunk), ntohs((chunk)->chunk_hdr->length) - sizeof(struct sctp_fwdtsn_chunk))
 
 #define _sctp_walk_fwdtsn(pos, chunk, end)\
-for (pos = chunk->subh.fwdtsn_hdr->skip;\
-     (void *)pos <= (void *)chunk->subh.fwdtsn_hdr->skip + end - sizeof(struct sctp_fwdtsn_skip);\
+for (pos = (void *)(chunk->subh.fwdtsn_hdr + 1);\
+     (void *)pos <= (void *)(chunk->subh.fwdtsn_hdr + 1) + end - sizeof(struct sctp_fwdtsn_skip);\
      pos++)
 
 /* External references. */

include/net/sctp/structs.h

@@ -332,7 +332,7 @@ struct sctp_cookie {
 	 * the association TCB is re-constructed from the cookie.
 	 */
 	__u32 raw_addr_list_len;
-	struct sctp_init_chunk peer_init[];
+	/* struct sctp_init_chunk peer_init[]; */
 };
 
 

net/sctp/associola.c

@@ -1597,9 +1597,10 @@ int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
 					 struct sctp_cookie *cookie,
 					 gfp_t gfp)
 {
-	int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
+	struct sctp_init_chunk *peer_init = (struct sctp_init_chunk *)(cookie + 1);
+	int var_size2 = ntohs(peer_init->chunk_hdr.length);
 	int var_size3 = cookie->raw_addr_list_len;
-	__u8 *raw = (__u8 *)cookie->peer_init + var_size2;
+	__u8 *raw = (__u8 *)peer_init + var_size2;
 
 	return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
 				      asoc->ep->base.bind_addr.port, gfp);

net/sctp/auth.c

@@ -738,7 +738,7 @@ void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
 
 	tfm = asoc->ep->auth_hmacs[hmac_id];
 
-	digest = auth->auth_hdr.hmac;
+	digest = (u8 *)(&auth->auth_hdr + 1);
 	if (crypto_shash_setkey(tfm, &asoc_key->data[0], asoc_key->len))
 		goto free;
 

net/sctp/input.c

@@ -1150,7 +1150,7 @@ static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
 	init = (struct sctp_init_chunk *)skb->data;
 
 	/* Walk the parameters looking for embedded addresses. */
-	sctp_walk_params(params, init, init_hdr.params) {
+	sctp_walk_params(params, init) {
 
 		/* Note: Ignoring hostname addresses. */
 		af = sctp_get_af_specific(param_type2af(params.p->type));

net/sctp/outqueue.c

@@ -1231,7 +1231,7 @@ static void sctp_sack_update_unack_data(struct sctp_association *assoc,
 
 	unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
 
-	frags = sack->variable;
+	frags = (union sctp_sack_variable *)(sack + 1);
 	for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
 		unack_data -= ((ntohs(frags[i].gab.end) -
 				ntohs(frags[i].gab.start) + 1));
@@ -1252,7 +1252,6 @@ int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
 	struct sctp_transport *transport;
 	struct sctp_chunk *tchunk = NULL;
 	struct list_head *lchunk, *transport_list, *temp;
-	union sctp_sack_variable *frags = sack->variable;
 	__u32 sack_ctsn, ctsn, tsn;
 	__u32 highest_tsn, highest_new_tsn;
 	__u32 sack_a_rwnd;
@@ -1313,8 +1312,12 @@ int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
 
 	/* Get the highest TSN in the sack. */
 	highest_tsn = sack_ctsn;
-	if (gap_ack_blocks)
+	if (gap_ack_blocks) {
+		union sctp_sack_variable *frags =
+			(union sctp_sack_variable *)(sack + 1);
+
 		highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
+	}
 
 	if (TSN_lt(asoc->highest_sacked, highest_tsn))
 		asoc->highest_sacked = highest_tsn;
@@ -1789,7 +1792,7 @@ static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
 	 *  Block are assumed to have been received correctly.
 	 */
 
-	frags = sack->variable;
+	frags = (union sctp_sack_variable *)(sack + 1);
 	blocks = ntohs(sack->num_gap_ack_blocks);
 	tsn_offset = tsn - ctsn;
 	for (i = 0; i < blocks; ++i) {

net/sctp/sm_make_chunk.c

@@ -1707,11 +1707,11 @@ static struct sctp_cookie_param *sctp_pack_cookie(
 					 ktime_get_real());
 
 	/* Copy the peer's init packet.  */
-	memcpy(&cookie->c.peer_init[0], init_chunk->chunk_hdr,
+	memcpy(cookie + 1, init_chunk->chunk_hdr,
 	       ntohs(init_chunk->chunk_hdr->length));
 
 	/* Copy the raw local address list of the association. */
-	memcpy((__u8 *)&cookie->c.peer_init[0] +
+	memcpy((__u8 *)(cookie + 1) +
 	       ntohs(init_chunk->chunk_hdr->length), raw_addrs, addrs_len);
 
 	if (sctp_sk(ep->base.sk)->hmac) {
@@ -2306,7 +2306,7 @@ int sctp_verify_init(struct net *net, const struct sctp_endpoint *ep,
 	    ntohl(peer_init->init_hdr.a_rwnd) < SCTP_DEFAULT_MINWINDOW)
 		return sctp_process_inv_mandatory(asoc, chunk, errp);
 
-	sctp_walk_params(param, peer_init, init_hdr.params) {
+	sctp_walk_params(param, peer_init) {
 		if (param.p->type == SCTP_PARAM_STATE_COOKIE)
 			has_cookie = true;
 	}
@@ -2329,7 +2329,7 @@ int sctp_verify_init(struct net *net, const struct sctp_endpoint *ep,
 						  chunk, errp);
 
 	/* Verify all the variable length parameters */
-	sctp_walk_params(param, peer_init, init_hdr.params) {
+	sctp_walk_params(param, peer_init) {
 		result = sctp_verify_param(net, ep, asoc, param, cid,
 					   chunk, errp);
 		switch (result) {
@@ -2381,7 +2381,7 @@ int sctp_process_init(struct sctp_association *asoc, struct sctp_chunk *chunk,
 		src_match = 1;
 
 	/* Process the initialization parameters.  */
-	sctp_walk_params(param, peer_init, init_hdr.params) {
+	sctp_walk_params(param, peer_init) {
 		if (!src_match &&
 		    (param.p->type == SCTP_PARAM_IPV4_ADDRESS ||
 		     param.p->type == SCTP_PARAM_IPV6_ADDRESS)) {
@@ -3202,7 +3202,7 @@ bool sctp_verify_asconf(const struct sctp_association *asoc,
 	union sctp_params param;
 
 	addip = (struct sctp_addip_chunk *)chunk->chunk_hdr;
-	sctp_walk_params(param, addip, addip_hdr.params) {
+	sctp_walk_params(param, addip) {
 		size_t length = ntohs(param.p->length);
 
 		*errp = param.p;
@@ -3215,14 +3215,14 @@ bool sctp_verify_asconf(const struct sctp_association *asoc,
 			/* ensure there is only one addr param and it's in the
 			 * beginning of addip_hdr params, or we reject it.
 			 */
-			if (param.v != addip->addip_hdr.params)
+			if (param.v != (addip + 1))
 				return false;
 			addr_param_seen = true;
 			break;
 		case SCTP_PARAM_IPV6_ADDRESS:
 			if (length != sizeof(struct sctp_ipv6addr_param))
 				return false;
-			if (param.v != addip->addip_hdr.params)
+			if (param.v != (addip + 1))
 				return false;
 			addr_param_seen = true;
 			break;
@@ -3302,7 +3302,7 @@ struct sctp_chunk *sctp_process_asconf(struct sctp_association *asoc,
 		goto done;
 
 	/* Process the TLVs contained within the ASCONF chunk. */
-	sctp_walk_params(param, addip, addip_hdr.params) {
+	sctp_walk_params(param, addip) {
 		/* Skip preceeding address parameters. */
 		if (param.p->type == SCTP_PARAM_IPV4_ADDRESS ||
 		    param.p->type == SCTP_PARAM_IPV6_ADDRESS)
@@ -3636,7 +3636,7 @@ static struct sctp_chunk *sctp_make_reconf(const struct sctp_association *asoc,
 		return NULL;
 
 	reconf = (struct sctp_reconf_chunk *)retval->chunk_hdr;
-	retval->param_hdr.v = reconf->params;
+	retval->param_hdr.v = (u8 *)(reconf + 1);
 
 	return retval;
 }
@@ -3878,7 +3878,7 @@ bool sctp_verify_reconf(const struct sctp_association *asoc,
 	__u16 cnt = 0;
 
 	hdr = (struct sctp_reconf_chunk *)chunk->chunk_hdr;
-	sctp_walk_params(param, hdr, params) {
+	sctp_walk_params(param, hdr) {
 		__u16 length = ntohs(param.p->length);
 
 		*errp = param.p;

net/sctp/sm_sideeffect.c

@@ -984,8 +984,7 @@ static void sctp_cmd_process_operr(struct sctp_cmd_seq *cmds,
 		{
 			struct sctp_chunkhdr *unk_chunk_hdr;
 
-			unk_chunk_hdr = (struct sctp_chunkhdr *)
-							err_hdr->variable;
+			unk_chunk_hdr = (struct sctp_chunkhdr *)(err_hdr + 1);
 			switch (unk_chunk_hdr->type) {
 			/* ADDIP 4.1 A9) If the peer responds to an ASCONF with
 			 * an ERROR chunk reporting that it did not recognized

net/sctp/sm_statefuns.c

@@ -794,8 +794,7 @@ enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net,
 	/* This is a brand-new association, so these are not yet side
 	 * effects--it is safe to run them here.
 	 */
-	peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
-
+	peer_init = (struct sctp_init_chunk *)(chunk->subh.cookie_hdr + 1);
 	if (!sctp_process_init(new_asoc, chunk,
 			       &chunk->subh.cookie_hdr->c.peer_addr,
 			       peer_init, GFP_ATOMIC))
@@ -1337,7 +1336,7 @@ static int sctp_sf_send_restart_abort(struct net *net, union sctp_addr *ssa,
 	 * throughout the code today.
 	 */
 	errhdr = (struct sctp_errhdr *)buffer;
-	addrparm = (union sctp_addr_param *)errhdr->variable;
+	addrparm = (union sctp_addr_param *)(errhdr + 1);
 
 	/* Copy into a parm format. */
 	len = af->to_addr_param(ssa, addrparm);
@@ -1869,8 +1868,7 @@ static enum sctp_disposition sctp_sf_do_dupcook_a(
 	/* new_asoc is a brand-new association, so these are not yet
 	 * side effects--it is safe to run them here.
 	 */
-	peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
-
+	peer_init = (struct sctp_init_chunk *)(chunk->subh.cookie_hdr + 1);
 	if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk), peer_init,
 			       GFP_ATOMIC))
 		goto nomem;
@@ -1990,7 +1988,7 @@ static enum sctp_disposition sctp_sf_do_dupcook_b(
 	/* new_asoc is a brand-new association, so these are not yet
 	 * side effects--it is safe to run them here.
 	 */
-	peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
+	peer_init = (struct sctp_init_chunk *)(chunk->subh.cookie_hdr + 1);
 	if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk), peer_init,
 			       GFP_ATOMIC))
 		goto nomem;
@@ -4142,7 +4140,7 @@ enum sctp_disposition sctp_sf_do_reconf(struct net *net,
 						  (void *)err_param, commands);
 
 	hdr = (struct sctp_reconf_chunk *)chunk->chunk_hdr;
-	sctp_walk_params(param, hdr, params) {
+	sctp_walk_params(param, hdr) {
 		struct sctp_chunk *reply = NULL;
 		struct sctp_ulpevent *ev = NULL;
 
@@ -4393,7 +4391,7 @@ static enum sctp_ierror sctp_sf_authenticate(
 	 *  3. Compute the new digest
 	 *  4. Compare saved and new digests.
 	 */
-	digest = auth_hdr->hmac;
+	digest = (u8 *)(auth_hdr + 1);
 	skb_pull(chunk->skb, sig_len);
 
 	save_digest = kmemdup(digest, sig_len, GFP_ATOMIC);