blob: 001080072b6b92ca9dd4545a7255fc7a51792f6f [file] [log] [blame]
Andrew Geissler90fd73c2021-03-05 15:25:55 -06001From dedcbd106f8e52d5586b0205bc7677e4c9868f9c Mon Sep 17 00:00:00 2001
2From: Will Cosgrove <will@panic.com>
3Date: Fri, 30 Aug 2019 09:57:38 -0700
4Subject: [PATCH] packet.c: improve message parsing (#402)
5
6* packet.c: improve parsing of packets
7
8file: packet.c
9
10notes:
11Use _libssh2_get_string API in SSH_MSG_DEBUG/SSH_MSG_DISCONNECT. Additional uint32 bounds check in SSH_MSG_GLOBAL_REQUEST.
12
13Upstream-Status: Backport
14CVE: CVE-2019-17498
15Signed-off-by: Li Zhou <li.zhou@windriver.com>
16---
17 src/packet.c | 68 ++++++++++++++++++++++------------------------------
18 1 file changed, 29 insertions(+), 39 deletions(-)
19
20diff --git a/src/packet.c b/src/packet.c
21index 38ab629..2e01bfc 100644
22--- a/src/packet.c
23+++ b/src/packet.c
24@@ -419,8 +419,8 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
25 size_t datalen, int macstate)
26 {
27 int rc = 0;
28- char *message = NULL;
29- char *language = NULL;
30+ unsigned char *message = NULL;
31+ unsigned char *language = NULL;
32 size_t message_len = 0;
33 size_t language_len = 0;
34 LIBSSH2_CHANNEL *channelp = NULL;
35@@ -472,33 +472,23 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
36
37 case SSH_MSG_DISCONNECT:
38 if(datalen >= 5) {
39- size_t reason = _libssh2_ntohu32(data + 1);
40+ uint32_t reason = 0;
41+ struct string_buf buf;
42+ buf.data = (unsigned char *)data;
43+ buf.dataptr = buf.data;
44+ buf.len = datalen;
45+ buf.dataptr++; /* advance past type */
46
47- if(datalen >= 9) {
48- message_len = _libssh2_ntohu32(data + 5);
49+ _libssh2_get_u32(&buf, &reason);
50+ _libssh2_get_string(&buf, &message, &message_len);
51+ _libssh2_get_string(&buf, &language, &language_len);
52
53- if(message_len < datalen-13) {
54- /* 9 = packet_type(1) + reason(4) + message_len(4) */
55- message = (char *) data + 9;
56-
57- language_len =
58- _libssh2_ntohu32(data + 9 + message_len);
59- language = (char *) data + 9 + message_len + 4;
60-
61- if(language_len > (datalen-13-message_len)) {
62- /* bad input, clear info */
63- language = message = NULL;
64- language_len = message_len = 0;
65- }
66- }
67- else
68- /* bad size, clear it */
69- message_len = 0;
70- }
71 if(session->ssh_msg_disconnect) {
72- LIBSSH2_DISCONNECT(session, reason, message,
73- message_len, language, language_len);
74+ LIBSSH2_DISCONNECT(session, reason, (const char *)message,
75+ message_len, (const char *)language,
76+ language_len);
77 }
78+
79 _libssh2_debug(session, LIBSSH2_TRACE_TRANS,
80 "Disconnect(%d): %s(%s)", reason,
81 message, language);
82@@ -539,24 +529,24 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
83 int always_display = data[1];
84
85 if(datalen >= 6) {
86- message_len = _libssh2_ntohu32(data + 2);
87-
88- if(message_len <= (datalen - 10)) {
89- /* 6 = packet_type(1) + display(1) + message_len(4) */
90- message = (char *) data + 6;
91- language_len = _libssh2_ntohu32(data + 6 +
92- message_len);
93-
94- if(language_len <= (datalen - 10 - message_len))
95- language = (char *) data + 10 + message_len;
96- }
97+ struct string_buf buf;
98+ buf.data = (unsigned char *)data;
99+ buf.dataptr = buf.data;
100+ buf.len = datalen;
101+ buf.dataptr += 2; /* advance past type & always display */
102+
103+ _libssh2_get_string(&buf, &message, &message_len);
104+ _libssh2_get_string(&buf, &language, &language_len);
105 }
106
107 if(session->ssh_msg_debug) {
108- LIBSSH2_DEBUG(session, always_display, message,
109- message_len, language, language_len);
110+ LIBSSH2_DEBUG(session, always_display,
111+ (const char *)message,
112+ message_len, (const char *)language,
113+ language_len);
114 }
115 }
116+
117 /*
118 * _libssh2_debug will actually truncate this for us so
119 * that it's not an inordinate about of data
120@@ -579,7 +569,7 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
121 uint32_t len = 0;
122 unsigned char want_reply = 0;
123 len = _libssh2_ntohu32(data + 1);
124- if(datalen >= (6 + len)) {
125+ if((len <= (UINT_MAX - 6)) && (datalen >= (6 + len))) {
126 want_reply = data[5 + len];
127 _libssh2_debug(session,
128 LIBSSH2_TRACE_CONN,
129--
1302.17.1
131