--- /dev/null
+From bbd951a21e0fd555cd9ede44c7196af09d04d171 Mon Sep 17 00:00:00 2001
+From: Daniel Borkmann <dborkman@redhat.com>
+Date: Thu, 9 Oct 2014 22:55:31 +0200
+Subject: [PATCH] net: sctp: fix skb_over_panic when receiving malformed ASCONF
+ chunks
+
+commit 9de7922bc709eee2f609cd01d98aaedc4cf5ea74 upstream.
+
+Commit 6f4c618ddb0 ("SCTP : Add paramters validity check for
+ASCONF chunk") added basic verification of ASCONF chunks, however,
+it is still possible to remotely crash a server by sending a
+special crafted ASCONF chunk, even up to pre 2.6.12 kernels:
+
+skb_over_panic: text:ffffffffa01ea1c3 len:31056 put:30768
+ head:ffff88011bd81800 data:ffff88011bd81800 tail:0x7950
+ end:0x440 dev:<NULL>
+ ------------[ cut here ]------------
+kernel BUG at net/core/skbuff.c:129!
+[...]
+Call Trace:
+ <IRQ>
+ [<ffffffff8144fb1c>] skb_put+0x5c/0x70
+ [<ffffffffa01ea1c3>] sctp_addto_chunk+0x63/0xd0 [sctp]
+ [<ffffffffa01eadaf>] sctp_process_asconf+0x1af/0x540 [sctp]
+ [<ffffffff8152d025>] ? _read_unlock_bh+0x15/0x20
+ [<ffffffffa01e0038>] sctp_sf_do_asconf+0x168/0x240 [sctp]
+ [<ffffffffa01e3751>] sctp_do_sm+0x71/0x1210 [sctp]
+ [<ffffffff8147645d>] ? fib_rules_lookup+0xad/0xf0
+ [<ffffffffa01e6b22>] ? sctp_cmp_addr_exact+0x32/0x40 [sctp]
+ [<ffffffffa01e8393>] sctp_assoc_bh_rcv+0xd3/0x180 [sctp]
+ [<ffffffffa01ee986>] sctp_inq_push+0x56/0x80 [sctp]
+ [<ffffffffa01fcc42>] sctp_rcv+0x982/0xa10 [sctp]
+ [<ffffffffa01d5123>] ? ipt_local_in_hook+0x23/0x28 [iptable_filter]
+ [<ffffffff8148bdc9>] ? nf_iterate+0x69/0xb0
+ [<ffffffff81496d10>] ? ip_local_deliver_finish+0x0/0x2d0
+ [<ffffffff8148bf86>] ? nf_hook_slow+0x76/0x120
+ [<ffffffff81496d10>] ? ip_local_deliver_finish+0x0/0x2d0
+ [<ffffffff81496ded>] ip_local_deliver_finish+0xdd/0x2d0
+ [<ffffffff81497078>] ip_local_deliver+0x98/0xa0
+ [<ffffffff8149653d>] ip_rcv_finish+0x12d/0x440
+ [<ffffffff81496ac5>] ip_rcv+0x275/0x350
+ [<ffffffff8145c88b>] __netif_receive_skb+0x4ab/0x750
+ [<ffffffff81460588>] netif_receive_skb+0x58/0x60
+
+This can be triggered e.g., through a simple scripted nmap
+connection scan injecting the chunk after the handshake, for
+example, ...
+
+ -------------- INIT[ASCONF; ASCONF_ACK] ------------->
+ <----------- INIT-ACK[ASCONF; ASCONF_ACK] ------------
+ -------------------- COOKIE-ECHO -------------------->
+ <-------------------- COOKIE-ACK ---------------------
+ ------------------ ASCONF; UNKNOWN ------------------>
+
+... where ASCONF chunk of length 280 contains 2 parameters ...
+
+ 1) Add IP address parameter (param length: 16)
+ 2) Add/del IP address parameter (param length: 255)
+
+... followed by an UNKNOWN chunk of e.g. 4 bytes. Here, the
+Address Parameter in the ASCONF chunk is even missing, too.
+This is just an example and similarly-crafted ASCONF chunks
+could be used just as well.
+
+The ASCONF chunk passes through sctp_verify_asconf() as all
+parameters passed sanity checks, and after walking, we ended
+up successfully at the chunk end boundary, and thus may invoke
+sctp_process_asconf(). Parameter walking is done with
+WORD_ROUND() to take padding into account.
+
+In sctp_process_asconf()'s TLV processing, we may fail in
+sctp_process_asconf_param() e.g., due to removal of the IP
+address that is also the source address of the packet containing
+the ASCONF chunk, and thus we need to add all TLVs after the
+failure to our ASCONF response to remote via helper function
+sctp_add_asconf_response(), which basically invokes a
+sctp_addto_chunk() adding the error parameters to the given
+skb.
+
+When walking to the next parameter this time, we proceed
+with ...
+
+ length = ntohs(asconf_param->param_hdr.length);
+ asconf_param = (void *)asconf_param + length;
+
+... instead of the WORD_ROUND()'ed length, thus resulting here
+in an off-by-one that leads to reading the follow-up garbage
+parameter length of 12336, and thus throwing an skb_over_panic
+for the reply when trying to sctp_addto_chunk() next time,
+which implicitly calls the skb_put() with that length.
+
+Fix it by using sctp_walk_params() [ which is also used in
+INIT parameter processing ] macro in the verification *and*
+in ASCONF processing: it will make sure we don't spill over,
+that we walk parameters WORD_ROUND()'ed. Moreover, we're being
+more defensive and guard against unknown parameter types and
+missized addresses.
+
+Joint work with Vlad Yasevich.
+
+Fixes CVE-2014-3673
+Upstream-Status: Backport
+
+Fixes: b896b82be4ae ("[SCTP] ADDIP: Support for processing incoming ASCONF_ACK chunks.")
+Signed-off-by: Daniel Borkmann <dborkman@redhat.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>
+Cc: Josh Boyer <jwboyer@fedoraproject.org>
+Signed-off-by: Jiri Slaby <jslaby@suse.cz>
+Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
+---
+ include/net/sctp/sm.h | 6 +--
+ net/sctp/sm_make_chunk.c | 99 +++++++++++++++++++++++++++---------------------
+ net/sctp/sm_statefuns.c | 18 +--------
+ 3 files changed, 60 insertions(+), 63 deletions(-)
+
+diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
+index 4ef75af..c91b6f5 100644
+--- a/include/net/sctp/sm.h
++++ b/include/net/sctp/sm.h
+@@ -249,9 +249,9 @@ struct sctp_chunk *sctp_make_asconf_update_ip(struct sctp_association *,
+ int, __be16);
+ struct sctp_chunk *sctp_make_asconf_set_prim(struct sctp_association *asoc,
+ union sctp_addr *addr);
+-int sctp_verify_asconf(const struct sctp_association *asoc,
+- struct sctp_paramhdr *param_hdr, void *chunk_end,
+- struct sctp_paramhdr **errp);
++bool sctp_verify_asconf(const struct sctp_association *asoc,
++ struct sctp_chunk *chunk, bool addr_param_needed,
++ struct sctp_paramhdr **errp);
+ struct sctp_chunk *sctp_process_asconf(struct sctp_association *asoc,
+ struct sctp_chunk *asconf);
+ int sctp_process_asconf_ack(struct sctp_association *asoc,
+diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
+index e342387..d800160 100644
+--- a/net/sctp/sm_make_chunk.c
++++ b/net/sctp/sm_make_chunk.c
+@@ -3126,50 +3126,63 @@ static __be16 sctp_process_asconf_param(struct sctp_association *asoc,
+ return SCTP_ERROR_NO_ERROR;
+ }
+
+-/* Verify the ASCONF packet before we process it. */
+-int sctp_verify_asconf(const struct sctp_association *asoc,
+- struct sctp_paramhdr *param_hdr, void *chunk_end,
+- struct sctp_paramhdr **errp) {
+- sctp_addip_param_t *asconf_param;
++/* Verify the ASCONF packet before we process it. */
++bool sctp_verify_asconf(const struct sctp_association *asoc,
++ struct sctp_chunk *chunk, bool addr_param_needed,
++ struct sctp_paramhdr **errp)
++{
++ sctp_addip_chunk_t *addip = (sctp_addip_chunk_t *) chunk->chunk_hdr;
+ union sctp_params param;
+- int length, plen;
+-
+- param.v = (sctp_paramhdr_t *) param_hdr;
+- while (param.v <= chunk_end - sizeof(sctp_paramhdr_t)) {
+- length = ntohs(param.p->length);
+- *errp = param.p;
++ bool addr_param_seen = false;
+
+- if (param.v > chunk_end - length ||
+- length < sizeof(sctp_paramhdr_t))
+- return 0;
++ sctp_walk_params(param, addip, addip_hdr.params) {
++ size_t length = ntohs(param.p->length);
+
++ *errp = param.p;
+ switch (param.p->type) {
++ case SCTP_PARAM_ERR_CAUSE:
++ break;
++ case SCTP_PARAM_IPV4_ADDRESS:
++ if (length != sizeof(sctp_ipv4addr_param_t))
++ return false;
++ addr_param_seen = true;
++ break;
++ case SCTP_PARAM_IPV6_ADDRESS:
++ if (length != sizeof(sctp_ipv6addr_param_t))
++ return false;
++ addr_param_seen = true;
++ break;
+ case SCTP_PARAM_ADD_IP:
+ case SCTP_PARAM_DEL_IP:
+ case SCTP_PARAM_SET_PRIMARY:
+- asconf_param = (sctp_addip_param_t *)param.v;
+- plen = ntohs(asconf_param->param_hdr.length);
+- if (plen < sizeof(sctp_addip_param_t) +
+- sizeof(sctp_paramhdr_t))
+- return 0;
++ /* In ASCONF chunks, these need to be first. */
++ if (addr_param_needed && !addr_param_seen)
++ return false;
++ length = ntohs(param.addip->param_hdr.length);
++ if (length < sizeof(sctp_addip_param_t) +
++ sizeof(sctp_paramhdr_t))
++ return false;
+ break;
+ case SCTP_PARAM_SUCCESS_REPORT:
+ case SCTP_PARAM_ADAPTATION_LAYER_IND:
+ if (length != sizeof(sctp_addip_param_t))
+- return 0;
+-
++ return false;
+ break;
+ default:
+- break;
++ /* This is unkown to us, reject! */
++ return false;
+ }
+-
+- param.v += WORD_ROUND(length);
+ }
+
+- if (param.v != chunk_end)
+- return 0;
++ /* Remaining sanity checks. */
++ if (addr_param_needed && !addr_param_seen)
++ return false;
++ if (!addr_param_needed && addr_param_seen)
++ return false;
++ if (param.v != chunk->chunk_end)
++ return false;
+
+- return 1;
++ return true;
+ }
+
+ /* Process an incoming ASCONF chunk with the next expected serial no. and
+@@ -3178,16 +3191,17 @@ int sctp_verify_asconf(const struct sctp_association *asoc,
+ struct sctp_chunk *sctp_process_asconf(struct sctp_association *asoc,
+ struct sctp_chunk *asconf)
+ {
++ sctp_addip_chunk_t *addip = (sctp_addip_chunk_t *) asconf->chunk_hdr;
++ bool all_param_pass = true;
++ union sctp_params param;
+ sctp_addiphdr_t *hdr;
+ union sctp_addr_param *addr_param;
+ sctp_addip_param_t *asconf_param;
+ struct sctp_chunk *asconf_ack;
+-
+ __be16 err_code;
+ int length = 0;
+ int chunk_len;
+ __u32 serial;
+- int all_param_pass = 1;
+
+ chunk_len = ntohs(asconf->chunk_hdr->length) - sizeof(sctp_chunkhdr_t);
+ hdr = (sctp_addiphdr_t *)asconf->skb->data;
+@@ -3215,9 +3229,14 @@ struct sctp_chunk *sctp_process_asconf(struct sctp_association *asoc,
+ goto done;
+
+ /* Process the TLVs contained within the ASCONF chunk. */
+- while (chunk_len > 0) {
++ sctp_walk_params(param, addip, addip_hdr.params) {
++ /* Skip preceeding address parameters. */
++ if (param.p->type == SCTP_PARAM_IPV4_ADDRESS ||
++ param.p->type == SCTP_PARAM_IPV6_ADDRESS)
++ continue;
++
+ err_code = sctp_process_asconf_param(asoc, asconf,
+- asconf_param);
++ param.addip);
+ /* ADDIP 4.1 A7)
+ * If an error response is received for a TLV parameter,
+ * all TLVs with no response before the failed TLV are
+@@ -3225,28 +3244,20 @@ struct sctp_chunk *sctp_process_asconf(struct sctp_association *asoc,
+ * the failed response are considered unsuccessful unless
+ * a specific success indication is present for the parameter.
+ */
+- if (SCTP_ERROR_NO_ERROR != err_code)
+- all_param_pass = 0;
+-
++ if (err_code != SCTP_ERROR_NO_ERROR)
++ all_param_pass = false;
+ if (!all_param_pass)
+- sctp_add_asconf_response(asconf_ack,
+- asconf_param->crr_id, err_code,
+- asconf_param);
++ sctp_add_asconf_response(asconf_ack, param.addip->crr_id,
++ err_code, param.addip);
+
+ /* ADDIP 4.3 D11) When an endpoint receiving an ASCONF to add
+ * an IP address sends an 'Out of Resource' in its response, it
+ * MUST also fail any subsequent add or delete requests bundled
+ * in the ASCONF.
+ */
+- if (SCTP_ERROR_RSRC_LOW == err_code)
++ if (err_code == SCTP_ERROR_RSRC_LOW)
+ goto done;
+-
+- /* Move to the next ASCONF param. */
+- length = ntohs(asconf_param->param_hdr.length);
+- asconf_param = (void *)asconf_param + length;
+- chunk_len -= length;
+ }
+-
+ done:
+ asoc->peer.addip_serial++;
+
+diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
+index 62623cc..bf12098 100644
+--- a/net/sctp/sm_statefuns.c
++++ b/net/sctp/sm_statefuns.c
+@@ -3595,9 +3595,7 @@ sctp_disposition_t sctp_sf_do_asconf(struct net *net,
+ struct sctp_chunk *asconf_ack = NULL;
+ struct sctp_paramhdr *err_param = NULL;
+ sctp_addiphdr_t *hdr;
+- union sctp_addr_param *addr_param;
+ __u32 serial;
+- int length;
+
+ if (!sctp_vtag_verify(chunk, asoc)) {
+ sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
+@@ -3622,17 +3620,8 @@ sctp_disposition_t sctp_sf_do_asconf(struct net *net,
+ hdr = (sctp_addiphdr_t *)chunk->skb->data;
+ serial = ntohl(hdr->serial);
+
+- addr_param = (union sctp_addr_param *)hdr->params;
+- length = ntohs(addr_param->p.length);
+- if (length < sizeof(sctp_paramhdr_t))
+- return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
+- (void *)addr_param, commands);
+-
+ /* Verify the ASCONF chunk before processing it. */
+- if (!sctp_verify_asconf(asoc,
+- (sctp_paramhdr_t *)((void *)addr_param + length),
+- (void *)chunk->chunk_end,
+- &err_param))
++ if (!sctp_verify_asconf(asoc, chunk, true, &err_param))
+ return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
+ (void *)err_param, commands);
+
+@@ -3750,10 +3739,7 @@ sctp_disposition_t sctp_sf_do_asconf_ack(struct net *net,
+ rcvd_serial = ntohl(addip_hdr->serial);
+
+ /* Verify the ASCONF-ACK chunk before processing it. */
+- if (!sctp_verify_asconf(asoc,
+- (sctp_paramhdr_t *)addip_hdr->params,
+- (void *)asconf_ack->chunk_end,
+- &err_param))
++ if (!sctp_verify_asconf(asoc, asconf_ack, false, &err_param))
+ return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
+ (void *)err_param, commands);
+
+--
+1.9.1
+
--- /dev/null
+From a723db0be941b8aebaa1a98b33d17a91b16603e4 Mon Sep 17 00:00:00 2001
+From: Daniel Borkmann <dborkman@redhat.com>
+Date: Thu, 9 Oct 2014 22:55:32 +0200
+Subject: [PATCH] net: sctp: fix panic on duplicate ASCONF chunks
+
+commit b69040d8e39f20d5215a03502a8e8b4c6ab78395 upstream.
+
+When receiving a e.g. semi-good formed connection scan in the
+form of ...
+
+ -------------- INIT[ASCONF; ASCONF_ACK] ------------->
+ <----------- INIT-ACK[ASCONF; ASCONF_ACK] ------------
+ -------------------- COOKIE-ECHO -------------------->
+ <-------------------- COOKIE-ACK ---------------------
+ ---------------- ASCONF_a; ASCONF_b ----------------->
+
+... where ASCONF_a equals ASCONF_b chunk (at least both serials
+need to be equal), we panic an SCTP server!
+
+The problem is that good-formed ASCONF chunks that we reply with
+ASCONF_ACK chunks are cached per serial. Thus, when we receive a
+same ASCONF chunk twice (e.g. through a lost ASCONF_ACK), we do
+not need to process them again on the server side (that was the
+idea, also proposed in the RFC). Instead, we know it was cached
+and we just resend the cached chunk instead. So far, so good.
+
+Where things get nasty is in SCTP's side effect interpreter, that
+is, sctp_cmd_interpreter():
+
+While incoming ASCONF_a (chunk = event_arg) is being marked
+!end_of_packet and !singleton, and we have an association context,
+we do not flush the outqueue the first time after processing the
+ASCONF_ACK singleton chunk via SCTP_CMD_REPLY. Instead, we keep it
+queued up, although we set local_cork to 1. Commit 2e3216cd54b1
+changed the precedence, so that as long as we get bundled, incoming
+chunks we try possible bundling on outgoing queue as well. Before
+this commit, we would just flush the output queue.
+
+Now, while ASCONF_a's ASCONF_ACK sits in the corked outq, we
+continue to process the same ASCONF_b chunk from the packet. As
+we have cached the previous ASCONF_ACK, we find it, grab it and
+do another SCTP_CMD_REPLY command on it. So, effectively, we rip
+the chunk->list pointers and requeue the same ASCONF_ACK chunk
+another time. Since we process ASCONF_b, it's correctly marked
+with end_of_packet and we enforce an uncork, and thus flush, thus
+crashing the kernel.
+
+Fix it by testing if the ASCONF_ACK is currently pending and if
+that is the case, do not requeue it. When flushing the output
+queue we may relink the chunk for preparing an outgoing packet,
+but eventually unlink it when it's copied into the skb right
+before transmission.
+
+Joint work with Vlad Yasevich.
+
+Fixes CVE-2014-3687
+Upstream-Status: Backport
+
+Fixes: 2e3216cd54b1 ("sctp: Follow security requirement of responding with 1 packet")
+Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
+Signed-off-by: Vlad Yasevich <vyasevich@gmail.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+Cc: Josh Boyer <jwboyer@fedoraproject.org>
+Signed-off-by: Jiri Slaby <jslaby@suse.cz>
+Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
+---
+ include/net/sctp/sctp.h | 5 +++++
+ net/sctp/associola.c | 2 ++
+ 2 files changed, 7 insertions(+)
+
+diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
+index 3794c5a..3848934 100644
+--- a/include/net/sctp/sctp.h
++++ b/include/net/sctp/sctp.h
+@@ -454,6 +454,11 @@ static inline void sctp_assoc_pending_pmtu(struct sock *sk, struct sctp_associat
+ asoc->pmtu_pending = 0;
+ }
+
++static inline bool sctp_chunk_pending(const struct sctp_chunk *chunk)
++{
++ return !list_empty(&chunk->list);
++}
++
+ /* Walk through a list of TLV parameters. Don't trust the
+ * individual parameter lengths and instead depend on
+ * the chunk length to indicate when to stop. Make sure
+diff --git a/net/sctp/associola.c b/net/sctp/associola.c
+index ad5cd6f..737050f 100644
+--- a/net/sctp/associola.c
++++ b/net/sctp/associola.c
+@@ -1645,6 +1645,8 @@ struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
+ * ack chunk whose serial number matches that of the request.
+ */
+ list_for_each_entry(ack, &asoc->asconf_ack_list, transmitted_list) {
++ if (sctp_chunk_pending(ack))
++ continue;
+ if (ack->subh.addip_hdr->serial == serial) {
+ sctp_chunk_hold(ack);
+ return ack;
+--
+1.9.1
+
--- /dev/null
+From e476841415c1b7b54e4118d8a219f5db71878675 Mon Sep 17 00:00:00 2001
+From: Daniel Borkmann <dborkman@redhat.com>
+Date: Thu, 9 Oct 2014 22:55:33 +0200
+Subject: [PATCH] net: sctp: fix remote memory pressure from excessive queueing
+
+commit 26b87c7881006311828bb0ab271a551a62dcceb4 upstream.
+
+This scenario is not limited to ASCONF, just taken as one
+example triggering the issue. When receiving ASCONF probes
+in the form of ...
+
+ -------------- INIT[ASCONF; ASCONF_ACK] ------------->
+ <----------- INIT-ACK[ASCONF; ASCONF_ACK] ------------
+ -------------------- COOKIE-ECHO -------------------->
+ <-------------------- COOKIE-ACK ---------------------
+ ---- ASCONF_a; [ASCONF_b; ...; ASCONF_n;] JUNK ------>
+ [...]
+ ---- ASCONF_m; [ASCONF_o; ...; ASCONF_z;] JUNK ------>
+
+... where ASCONF_a, ASCONF_b, ..., ASCONF_z are good-formed
+ASCONFs and have increasing serial numbers, we process such
+ASCONF chunk(s) marked with !end_of_packet and !singleton,
+since we have not yet reached the SCTP packet end. SCTP does
+only do verification on a chunk by chunk basis, as an SCTP
+packet is nothing more than just a container of a stream of
+chunks which it eats up one by one.
+
+We could run into the case that we receive a packet with a
+malformed tail, above marked as trailing JUNK. All previous
+chunks are here goodformed, so the stack will eat up all
+previous chunks up to this point. In case JUNK does not fit
+into a chunk header and there are no more other chunks in
+the input queue, or in case JUNK contains a garbage chunk
+header, but the encoded chunk length would exceed the skb
+tail, or we came here from an entirely different scenario
+and the chunk has pdiscard=1 mark (without having had a flush
+point), it will happen, that we will excessively queue up
+the association's output queue (a correct final chunk may
+then turn it into a response flood when flushing the
+queue ;)): I ran a simple script with incremental ASCONF
+serial numbers and could see the server side consuming
+excessive amount of RAM [before/after: up to 2GB and more].
+
+The issue at heart is that the chunk train basically ends
+with !end_of_packet and !singleton markers and since commit
+2e3216cd54b1 ("sctp: Follow security requirement of responding
+with 1 packet") therefore preventing an output queue flush
+point in sctp_do_sm() -> sctp_cmd_interpreter() on the input
+chunk (chunk = event_arg) even though local_cork is set,
+but its precedence has changed since then. In the normal
+case, the last chunk with end_of_packet=1 would trigger the
+queue flush to accommodate possible outgoing bundling.
+
+In the input queue, sctp_inq_pop() seems to do the right thing
+in terms of discarding invalid chunks. So, above JUNK will
+not enter the state machine and instead be released and exit
+the sctp_assoc_bh_rcv() chunk processing loop. It's simply
+the flush point being missing at loop exit. Adding a try-flush
+approach on the output queue might not work as the underlying
+infrastructure might be long gone at this point due to the
+side-effect interpreter run.
+
+One possibility, albeit a bit of a kludge, would be to defer
+invalid chunk freeing into the state machine in order to
+possibly trigger packet discards and thus indirectly a queue
+flush on error. It would surely be better to discard chunks
+as in the current, perhaps better controlled environment, but
+going back and forth, it's simply architecturally not possible.
+I tried various trailing JUNK attack cases and it seems to
+look good now.
+
+Joint work with Vlad Yasevich.
+
+Fixes CVE-2014-3688
+Upstream-Status: Backport
+
+Fixes: 2e3216cd54b1 ("sctp: Follow security requirement of responding with 1 packet")
+Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
+Signed-off-by: Vlad Yasevich <vyasevich@gmail.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+Cc: Josh Boyer <jwboyer@fedoraproject.org>
+Signed-off-by: Jiri Slaby <jslaby@suse.cz>
+Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
+---
+ net/sctp/inqueue.c | 33 +++++++--------------------------
+ net/sctp/sm_statefuns.c | 3 +++
+ 2 files changed, 10 insertions(+), 26 deletions(-)
+
+diff --git a/net/sctp/inqueue.c b/net/sctp/inqueue.c
+index 5856932..560cd41 100644
+--- a/net/sctp/inqueue.c
++++ b/net/sctp/inqueue.c
+@@ -141,18 +141,9 @@ struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
+ } else {
+ /* Nothing to do. Next chunk in the packet, please. */
+ ch = (sctp_chunkhdr_t *) chunk->chunk_end;
+-
+ /* Force chunk->skb->data to chunk->chunk_end. */
+- skb_pull(chunk->skb,
+- chunk->chunk_end - chunk->skb->data);
+-
+- /* Verify that we have at least chunk headers
+- * worth of buffer left.
+- */
+- if (skb_headlen(chunk->skb) < sizeof(sctp_chunkhdr_t)) {
+- sctp_chunk_free(chunk);
+- chunk = queue->in_progress = NULL;
+- }
++ skb_pull(chunk->skb, chunk->chunk_end - chunk->skb->data);
++ /* We are guaranteed to pull a SCTP header. */
+ }
+ }
+
+@@ -188,24 +179,14 @@ struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
+ skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
+ chunk->subh.v = NULL; /* Subheader is no longer valid. */
+
+- if (chunk->chunk_end < skb_tail_pointer(chunk->skb)) {
++ if (chunk->chunk_end + sizeof(sctp_chunkhdr_t) <
++ skb_tail_pointer(chunk->skb)) {
+ /* This is not a singleton */
+ chunk->singleton = 0;
+ } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {
+- /* RFC 2960, Section 6.10 Bundling
+- *
+- * Partial chunks MUST NOT be placed in an SCTP packet.
+- * If the receiver detects a partial chunk, it MUST drop
+- * the chunk.
+- *
+- * Since the end of the chunk is past the end of our buffer
+- * (which contains the whole packet, we can freely discard
+- * the whole packet.
+- */
+- sctp_chunk_free(chunk);
+- chunk = queue->in_progress = NULL;
+-
+- return NULL;
++ /* Discard inside state machine. */
++ chunk->pdiscard = 1;
++ chunk->chunk_end = skb_tail_pointer(chunk->skb);
+ } else {
+ /* We are at the end of the packet, so mark the chunk
+ * in case we need to send a SACK.
+diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
+index 1dbcc6a..62623cc 100644
+--- a/net/sctp/sm_statefuns.c
++++ b/net/sctp/sm_statefuns.c
+@@ -171,6 +171,9 @@ sctp_chunk_length_valid(struct sctp_chunk *chunk,
+ {
+ __u16 chunk_length = ntohs(chunk->chunk_hdr->length);
+
++ /* Previously already marked? */
++ if (unlikely(chunk->pdiscard))
++ return 0;
+ if (unlikely(chunk_length < required_length))
+ return 0;
+
+--
+1.9.1
+
