1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
|
From a004e72b95835136d3f1ea90517f706c24c03da7 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Thu, 5 May 2016 11:10:26 +0100
Subject: [PATCH] Avoid some undefined pointer arithmetic
A common idiom in the codebase is:
if (p + len > limit)
{
return; /* Too long */
}
Where "p" points to some malloc'd data of SIZE bytes and
limit == p + SIZE
"len" here could be from some externally supplied data (e.g. from a TLS
message).
The rules of C pointer arithmetic are such that "p + len" is only well
defined where len <= SIZE. Therefore the above idiom is actually
undefined behaviour.
For example this could cause problems if some malloc implementation
provides an address for "p" such that "p + len" actually overflows for
values of len that are too big and therefore p + len < limit!
Issue reported by Guido Vranken.
CVE-2016-2177
Reviewed-by: Rich Salz <rsalz@openssl.org>
---
ssl/s3_srvr.c | 14 +++++++-------
ssl/ssl_sess.c | 2 +-
ssl/t1_lib.c | 56 ++++++++++++++++++++++++++++++--------------------------
3 files changed, 38 insertions(+), 34 deletions(-)
diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
index ab28702..ab7f690 100644
--- a/ssl/s3_srvr.c
+++ b/ssl/s3_srvr.c
@@ -980,7 +980,7 @@ int ssl3_get_client_hello(SSL *s)
session_length = *(p + SSL3_RANDOM_SIZE);
- if (p + SSL3_RANDOM_SIZE + session_length + 1 >= d + n) {
+ if (SSL3_RANDOM_SIZE + session_length + 1 >= (d + n) - p) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
@@ -998,7 +998,7 @@ int ssl3_get_client_hello(SSL *s)
/* get the session-id */
j = *(p++);
- if (p + j > d + n) {
+ if ((d + n) - p < j) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
@@ -1054,14 +1054,14 @@ int ssl3_get_client_hello(SSL *s)
if (SSL_IS_DTLS(s)) {
/* cookie stuff */
- if (p + 1 > d + n) {
+ if ((d + n) - p < 1) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
}
cookie_len = *(p++);
- if (p + cookie_len > d + n) {
+ if ((d + n ) - p < cookie_len) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
@@ -1131,7 +1131,7 @@ int ssl3_get_client_hello(SSL *s)
}
}
- if (p + 2 > d + n) {
+ if ((d + n ) - p < 2) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
@@ -1145,7 +1145,7 @@ int ssl3_get_client_hello(SSL *s)
}
/* i bytes of cipher data + 1 byte for compression length later */
- if ((p + i + 1) > (d + n)) {
+ if ((d + n) - p < i + 1) {
/* not enough data */
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_MISMATCH);
@@ -1211,7 +1211,7 @@ int ssl3_get_client_hello(SSL *s)
/* compression */
i = *(p++);
- if ((p + i) > (d + n)) {
+ if ((d + n) - p < i) {
/* not enough data */
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_MISMATCH);
diff --git a/ssl/ssl_sess.c b/ssl/ssl_sess.c
index b182998..54ee783 100644
--- a/ssl/ssl_sess.c
+++ b/ssl/ssl_sess.c
@@ -573,7 +573,7 @@ int ssl_get_prev_session(SSL *s, unsigned char *session_id, int len,
int r;
#endif
- if (session_id + len > limit) {
+ if (limit - session_id < len) {
fatal = 1;
goto err;
}
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index fb64607..cdac011 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -1867,11 +1867,11 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data,
0x02, 0x03, /* SHA-1/ECDSA */
};
- if (data >= (limit - 2))
+ if (limit - data <= 2)
return;
data += 2;
- if (data > (limit - 4))
+ if (limit - data < 4)
return;
n2s(data, type);
n2s(data, size);
@@ -1879,7 +1879,7 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data,
if (type != TLSEXT_TYPE_server_name)
return;
- if (data + size > limit)
+ if (limit - data < size)
return;
data += size;
@@ -1887,7 +1887,7 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data,
const size_t len1 = sizeof(kSafariExtensionsBlock);
const size_t len2 = sizeof(kSafariTLS12ExtensionsBlock);
- if (data + len1 + len2 != limit)
+ if (limit - data != (int)(len1 + len2))
return;
if (memcmp(data, kSafariExtensionsBlock, len1) != 0)
return;
@@ -1896,7 +1896,7 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data,
} else {
const size_t len = sizeof(kSafariExtensionsBlock);
- if (data + len != limit)
+ if (limit - data != (int)(len))
return;
if (memcmp(data, kSafariExtensionsBlock, len) != 0)
return;
@@ -2053,19 +2053,19 @@ static int ssl_scan_clienthello_tlsext(SSL *s, unsigned char **p,
if (data == limit)
goto ri_check;
- if (data > (limit - 2))
+ if (limit - data < 2)
goto err;
n2s(data, len);
- if (data + len != limit)
+ if (limit - data != len)
goto err;
- while (data <= (limit - 4)) {
+ while (limit - data >= 4) {
n2s(data, type);
n2s(data, size);
- if (data + size > (limit))
+ if (limit - data < size)
goto err;
# if 0
fprintf(stderr, "Received extension type %d size %d\n", type, size);
@@ -2472,18 +2472,18 @@ static int ssl_scan_clienthello_custom_tlsext(SSL *s,
if (s->hit || s->cert->srv_ext.meths_count == 0)
return 1;
- if (data >= limit - 2)
+ if (limit - data <= 2)
return 1;
n2s(data, len);
- if (data > limit - len)
+ if (limit - data < len)
return 1;
- while (data <= limit - 4) {
+ while (limit - data >= 4) {
n2s(data, type);
n2s(data, size);
- if (data + size > limit)
+ if (limit - data < size)
return 1;
if (custom_ext_parse(s, 1 /* server */ , type, data, size, al) <= 0)
return 0;
@@ -2569,20 +2569,20 @@ static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,
SSL_TLSEXT_HB_DONT_SEND_REQUESTS);
# endif
- if (data >= (d + n - 2))
+ if ((d + n) - data <= 2)
goto ri_check;
n2s(data, length);
- if (data + length != d + n) {
+ if ((d + n) - data != length) {
*al = SSL_AD_DECODE_ERROR;
return 0;
}
- while (data <= (d + n - 4)) {
+ while ((d + n) - data >= 4) {
n2s(data, type);
n2s(data, size);
- if (data + size > (d + n))
+ if ((d + n) - data < size)
goto ri_check;
if (s->tlsext_debug_cb)
@@ -3307,29 +3307,33 @@ int tls1_process_ticket(SSL *s, unsigned char *session_id, int len,
/* Skip past DTLS cookie */
if (SSL_IS_DTLS(s)) {
i = *(p++);
- p += i;
- if (p >= limit)
+
+ if (limit - p <= i)
return -1;
+
+ p += i;
}
/* Skip past cipher list */
n2s(p, i);
- p += i;
- if (p >= limit)
+ if (limit - p <= i)
return -1;
+ p += i;
+
/* Skip past compression algorithm list */
i = *(p++);
- p += i;
- if (p > limit)
+ if (limit - p < i)
return -1;
+ p += i;
+
/* Now at start of extensions */
- if ((p + 2) >= limit)
+ if (limit - p <= 2)
return 0;
n2s(p, i);
- while ((p + 4) <= limit) {
+ while (limit - p >= 4) {
unsigned short type, size;
n2s(p, type);
n2s(p, size);
- if (p + size > limit)
+ if (limit - p < size)
return 0;
if (type == TLSEXT_TYPE_session_ticket) {
int r;
--
1.9.1
|
