File 0011-bgpd-avoid-notify-race-between-io-and-main-pthreads.patch of Package frr
From d6bbc7e4545ff8a766f3863764e3d0aa968e1932 Mon Sep 17 00:00:00 2001
From: Mark Stapp <mstapp@nvidia.com>
Date: Thu, 8 Sep 2022 16:14:36 -0400
References: CVE-2022-37035,bsc#1202085
Upstream: yes
Subject: [PATCH] bgpd: avoid notify race between io and main pthreads
The "bgp_notify_" apis in bgp_packet.c generate a notification
to a peer, usually during error handling. The io pthread wants
to send notifications in a couple of cases during early
received-packet validation - but the existing api interacts
with the peer struct itself, and that's not safe.
Add a new api for use by the io pthread, and adjust the main
notify api so that it can avoid touching the peer struct.
Signed-off-by: Mark Stapp <mstapp@nvidia.com>
diff --git a/bgpd/bgp_io.c b/bgpd/bgp_io.c
index ab50c545b5..03b2086559 100644
--- a/bgpd/bgp_io.c
+++ b/bgpd/bgp_io.c
@@ -38,7 +38,7 @@
#include "bgpd/bgp_debug.h" // for bgp_debug_neighbor_events, bgp_type_str
#include "bgpd/bgp_errors.h" // for expanded error reference information
#include "bgpd/bgp_fsm.h" // for BGP_EVENT_ADD, bgp_event
-#include "bgpd/bgp_packet.h" // for bgp_notify_send_with_data, bgp_notify...
+#include "bgpd/bgp_packet.h" // for bgp_notify_io_invalid...
#include "bgpd/bgpd.h" // for peer, BGP_MARKER_SIZE, bgp_master, bm
/* clang-format on */
@@ -523,8 +523,8 @@ static bool validate_header(struct peer *peer)
return false;
if (memcmp(m_correct, m_rx, BGP_MARKER_SIZE) != 0) {
- bgp_notify_send(peer, BGP_NOTIFY_HEADER_ERR,
- BGP_NOTIFY_HEADER_NOT_SYNC);
+ bgp_notify_io_invalid(peer, BGP_NOTIFY_HEADER_ERR,
+ BGP_NOTIFY_HEADER_NOT_SYNC, NULL, 0);
return false;
}
@@ -544,9 +544,8 @@ static bool validate_header(struct peer *peer)
zlog_debug("%s unknown message type 0x%02x", peer->host,
type);
- bgp_notify_send_with_data(peer, BGP_NOTIFY_HEADER_ERR,
- BGP_NOTIFY_HEADER_BAD_MESTYPE, &type,
- 1);
+ bgp_notify_io_invalid(peer, BGP_NOTIFY_HEADER_ERR,
+ BGP_NOTIFY_HEADER_BAD_MESTYPE, &type, 1);
return false;
}
@@ -571,9 +570,9 @@ static bool validate_header(struct peer *peer)
uint16_t nsize = htons(size);
- bgp_notify_send_with_data(peer, BGP_NOTIFY_HEADER_ERR,
- BGP_NOTIFY_HEADER_BAD_MESLEN,
- (unsigned char *)&nsize, 2);
+ bgp_notify_io_invalid(peer, BGP_NOTIFY_HEADER_ERR,
+ BGP_NOTIFY_HEADER_BAD_MESLEN,
+ (unsigned char *)&nsize, 2);
return false;
}
diff --git a/bgpd/bgp_packet.c b/bgpd/bgp_packet.c
index 4f7e7c8cba..28ed541a4a 100644
--- a/bgpd/bgp_packet.c
+++ b/bgpd/bgp_packet.c
@@ -674,8 +674,9 @@ static void bgp_write_notify(struct peer *peer)
* @param data Data portion
* @param datalen length of data portion
*/
-void bgp_notify_send_with_data(struct peer *peer, uint8_t code,
- uint8_t sub_code, uint8_t *data, size_t datalen)
+static void bgp_notify_send_internal(struct peer *peer, uint8_t code,
+ uint8_t sub_code, uint8_t *data,
+ size_t datalen, bool use_curr)
{
struct stream *s;
@@ -707,8 +708,11 @@ void bgp_notify_send_with_data(struct peer *peer, uint8_t code,
* If possible, store last packet for debugging purposes. This check is
* in place because we are sometimes called with a doppelganger peer,
* who tends to have a plethora of fields nulled out.
+ *
+ * Some callers should not attempt this - the io pthread for example
+ * should not touch internals of the peer struct.
*/
- if (peer->curr) {
+ if (use_curr && peer->curr) {
size_t packetsize = stream_get_endp(peer->curr);
assert(packetsize <= sizeof(peer->last_reset_cause));
memcpy(peer->last_reset_cause, peer->curr->data, packetsize);
@@ -791,7 +795,27 @@ void bgp_notify_send_with_data(struct peer *peer, uint8_t code,
*/
void bgp_notify_send(struct peer *peer, uint8_t code, uint8_t sub_code)
{
- bgp_notify_send_with_data(peer, code, sub_code, NULL, 0);
+ bgp_notify_send_internal(peer, code, sub_code, NULL, 0, true);
+}
+
+/*
+ * Enqueue notification; called from the main pthread, peer object access is ok.
+ */
+void bgp_notify_send_with_data(struct peer *peer, uint8_t code,
+ uint8_t sub_code, uint8_t *data, size_t datalen)
+{
+ bgp_notify_send_internal(peer, code, sub_code, data, datalen, true);
+}
+
+/*
+ * For use by the io pthread, queueing a notification but avoiding access to
+ * the peer object.
+ */
+void bgp_notify_io_invalid(struct peer *peer, uint8_t code, uint8_t sub_code,
+ uint8_t *data, size_t datalen)
+{
+ /* Avoid touching the peer object */
+ bgp_notify_send_internal(peer, code, sub_code, data, datalen, false);
}
/*
diff --git a/bgpd/bgp_packet.h b/bgpd/bgp_packet.h
index e83f7d950c..62028175d1 100644
--- a/bgpd/bgp_packet.h
+++ b/bgpd/bgp_packet.h
@@ -62,6 +62,8 @@ extern void bgp_open_send(struct peer *);
extern void bgp_notify_send(struct peer *, uint8_t, uint8_t);
extern void bgp_notify_send_with_data(struct peer *, uint8_t, uint8_t,
uint8_t *, size_t);
+void bgp_notify_io_invalid(struct peer *peer, uint8_t code, uint8_t sub_code,
+ uint8_t *data, size_t datalen);
extern void bgp_route_refresh_send(struct peer *, afi_t, safi_t, uint8_t,
uint8_t, int);
extern void bgp_capability_send(struct peer *, afi_t, safi_t, int, int);
--
2.35.3
