From 9aa422ad326634b76309e8ff342c246800621216 Mon Sep 17 00:00:00 2001
From: Jon Maloy <jmaloy@redhat.com>
Date: Sat, 5 Feb 2022 14:11:18 -0500
Subject: [PATCH] tipc: improve size validations for received domain records
Git-commit: 9aa422ad326634b76309e8ff342c246800621216
Patch-mainline: v5.17-rc3
References: bsc#1195254, CVE-2022-0435

The function tipc_mon_rcv() allows a node to receive and process
domain_record structs from peer nodes to track their views of the
network topology.

This patch verifies that the number of members in a received domain
record does not exceed the limit defined by MAX_MON_DOMAIN, something
that may otherwise lead to a stack overflow.

tipc_mon_rcv() is called from the function tipc_link_proto_rcv(), where
we are reading a 32 bit message data length field into a uint16.  To
avert any risk of bit overflow, we add an extra sanity check for this in
that function.  We cannot see that happen with the current code, but
future designers being unaware of this risk, may introduce it by
allowing delivery of very large (> 64k) sk buffers from the bearer
layer.  This potential problem was identified by Eric Dumazet.

This fixes CVE-2022-0435

Reported-by: Samuel Page <samuel.page@appgate.com>
Reported-by: Eric Dumazet <edumazet@google.com>
Fixes: 35c55c9877f8 ("tipc: add neighbor monitoring framework")
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Samuel Page <samuel.page@appgate.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
 net/tipc/link.c    | 9 +++++++--
 net/tipc/monitor.c | 2 ++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/net/tipc/link.c b/net/tipc/link.c
index 8d9e09f48f4c..1e14d7f8f28f 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -1444,13 +1444,16 @@ static int tipc_link_proto_rcv(struct ti
 	u16 peers_tol = msg_link_tolerance(hdr);
 	u16 peers_prio = msg_linkprio(hdr);
 	u16 rcv_nxt = l->rcv_nxt;
-	u16 dlen = msg_data_sz(hdr);
+	u32 dlen = msg_data_sz(hdr);
 	int mtyp = msg_type(hdr);
 	bool reply = msg_probe(hdr);
 	void *data;
 	char *if_name;
 	int rc = 0;
 
+	if (dlen > U16_MAX)
+		goto exit;
+
 	if (tipc_link_is_blocked(l) || !xmitq)
 		goto exit;
 
diff --git a/net/tipc/monitor.c b/net/tipc/monitor.c
index 407619697292..2f4d23238a7e 100644
--- a/net/tipc/monitor.c
+++ b/net/tipc/monitor.c
@@ -496,6 +496,8 @@ void tipc_mon_rcv(struct net *net, void *data, u16 dlen, u32 addr,
 	state->probing = false;
 
 	/* Sanity check received domain record */
+	if (new_member_cnt > MAX_MON_DOMAIN)
+		return;
 	if (dlen < dom_rec_len(arrv_dom, 0))
 		return;
 	if (dlen != dom_rec_len(arrv_dom, new_member_cnt))
-- 
2.16.4