287 lines
8.1 KiB
Diff
287 lines
8.1 KiB
Diff
Fix CVE-2016-2177.
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<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2177>
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Source:
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<https://git.openssl.org/?p=openssl.git;a=commit;h=a004e72b95835136d3f1ea90517f706c24c03da7>
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From a004e72b95835136d3f1ea90517f706c24c03da7 Mon Sep 17 00:00:00 2001
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From: Matt Caswell <matt@openssl.org>
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Date: Thu, 5 May 2016 11:10:26 +0100
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Subject: [PATCH] Avoid some undefined pointer arithmetic
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A common idiom in the codebase is:
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if (p + len > limit)
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{
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return; /* Too long */
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}
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Where "p" points to some malloc'd data of SIZE bytes and
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limit == p + SIZE
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"len" here could be from some externally supplied data (e.g. from a TLS
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message).
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The rules of C pointer arithmetic are such that "p + len" is only well
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defined where len <= SIZE. Therefore the above idiom is actually
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undefined behaviour.
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For example this could cause problems if some malloc implementation
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provides an address for "p" such that "p + len" actually overflows for
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values of len that are too big and therefore p + len < limit!
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Issue reported by Guido Vranken.
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CVE-2016-2177
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Reviewed-by: Rich Salz <rsalz@openssl.org>
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---
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ssl/s3_srvr.c | 14 +++++++-------
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ssl/ssl_sess.c | 2 +-
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ssl/t1_lib.c | 56 ++++++++++++++++++++++++++++++--------------------------
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3 files changed, 38 insertions(+), 34 deletions(-)
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diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
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index ab28702..ab7f690 100644
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--- a/ssl/s3_srvr.c
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+++ b/ssl/s3_srvr.c
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@@ -980,7 +980,7 @@ int ssl3_get_client_hello(SSL *s)
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session_length = *(p + SSL3_RANDOM_SIZE);
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- if (p + SSL3_RANDOM_SIZE + session_length + 1 >= d + n) {
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+ if (SSL3_RANDOM_SIZE + session_length + 1 >= (d + n) - p) {
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al = SSL_AD_DECODE_ERROR;
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SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
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goto f_err;
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@@ -998,7 +998,7 @@ int ssl3_get_client_hello(SSL *s)
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/* get the session-id */
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j = *(p++);
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- if (p + j > d + n) {
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+ if ((d + n) - p < j) {
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al = SSL_AD_DECODE_ERROR;
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SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
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goto f_err;
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@@ -1054,14 +1054,14 @@ int ssl3_get_client_hello(SSL *s)
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if (SSL_IS_DTLS(s)) {
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/* cookie stuff */
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- if (p + 1 > d + n) {
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+ if ((d + n) - p < 1) {
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al = SSL_AD_DECODE_ERROR;
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SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
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goto f_err;
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}
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cookie_len = *(p++);
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- if (p + cookie_len > d + n) {
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+ if ((d + n ) - p < cookie_len) {
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al = SSL_AD_DECODE_ERROR;
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SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
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goto f_err;
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@@ -1131,7 +1131,7 @@ int ssl3_get_client_hello(SSL *s)
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}
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}
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- if (p + 2 > d + n) {
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+ if ((d + n ) - p < 2) {
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al = SSL_AD_DECODE_ERROR;
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SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
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goto f_err;
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@@ -1145,7 +1145,7 @@ int ssl3_get_client_hello(SSL *s)
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}
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/* i bytes of cipher data + 1 byte for compression length later */
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- if ((p + i + 1) > (d + n)) {
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+ if ((d + n) - p < i + 1) {
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/* not enough data */
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al = SSL_AD_DECODE_ERROR;
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SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_MISMATCH);
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@@ -1211,7 +1211,7 @@ int ssl3_get_client_hello(SSL *s)
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/* compression */
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i = *(p++);
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- if ((p + i) > (d + n)) {
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+ if ((d + n) - p < i) {
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/* not enough data */
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al = SSL_AD_DECODE_ERROR;
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SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_MISMATCH);
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diff --git a/ssl/ssl_sess.c b/ssl/ssl_sess.c
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index b182998..54ee783 100644
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--- a/ssl/ssl_sess.c
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+++ b/ssl/ssl_sess.c
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@@ -573,7 +573,7 @@ int ssl_get_prev_session(SSL *s, unsigned char *session_id, int len,
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int r;
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#endif
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- if (session_id + len > limit) {
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+ if (limit - session_id < len) {
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fatal = 1;
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goto err;
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}
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diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
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index fb64607..cdac011 100644
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--- a/ssl/t1_lib.c
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+++ b/ssl/t1_lib.c
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@@ -1867,11 +1867,11 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data,
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0x02, 0x03, /* SHA-1/ECDSA */
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};
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- if (data >= (limit - 2))
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+ if (limit - data <= 2)
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return;
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data += 2;
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- if (data > (limit - 4))
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+ if (limit - data < 4)
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return;
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n2s(data, type);
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n2s(data, size);
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@@ -1879,7 +1879,7 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data,
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if (type != TLSEXT_TYPE_server_name)
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return;
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- if (data + size > limit)
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+ if (limit - data < size)
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return;
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data += size;
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@@ -1887,7 +1887,7 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data,
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const size_t len1 = sizeof(kSafariExtensionsBlock);
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const size_t len2 = sizeof(kSafariTLS12ExtensionsBlock);
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- if (data + len1 + len2 != limit)
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+ if (limit - data != (int)(len1 + len2))
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return;
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if (memcmp(data, kSafariExtensionsBlock, len1) != 0)
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return;
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@@ -1896,7 +1896,7 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data,
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} else {
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const size_t len = sizeof(kSafariExtensionsBlock);
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- if (data + len != limit)
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+ if (limit - data != (int)(len))
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return;
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if (memcmp(data, kSafariExtensionsBlock, len) != 0)
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return;
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@@ -2053,19 +2053,19 @@ static int ssl_scan_clienthello_tlsext(SSL *s, unsigned char **p,
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if (data == limit)
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goto ri_check;
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- if (data > (limit - 2))
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+ if (limit - data < 2)
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goto err;
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n2s(data, len);
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- if (data + len != limit)
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+ if (limit - data != len)
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goto err;
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- while (data <= (limit - 4)) {
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+ while (limit - data >= 4) {
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n2s(data, type);
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n2s(data, size);
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- if (data + size > (limit))
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+ if (limit - data < size)
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goto err;
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# if 0
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fprintf(stderr, "Received extension type %d size %d\n", type, size);
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@@ -2472,18 +2472,18 @@ static int ssl_scan_clienthello_custom_tlsext(SSL *s,
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if (s->hit || s->cert->srv_ext.meths_count == 0)
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return 1;
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- if (data >= limit - 2)
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+ if (limit - data <= 2)
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return 1;
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n2s(data, len);
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- if (data > limit - len)
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+ if (limit - data < len)
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return 1;
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- while (data <= limit - 4) {
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+ while (limit - data >= 4) {
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n2s(data, type);
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n2s(data, size);
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- if (data + size > limit)
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+ if (limit - data < size)
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return 1;
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if (custom_ext_parse(s, 1 /* server */ , type, data, size, al) <= 0)
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return 0;
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@@ -2569,20 +2569,20 @@ static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,
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SSL_TLSEXT_HB_DONT_SEND_REQUESTS);
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# endif
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- if (data >= (d + n - 2))
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+ if ((d + n) - data <= 2)
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goto ri_check;
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n2s(data, length);
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- if (data + length != d + n) {
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+ if ((d + n) - data != length) {
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*al = SSL_AD_DECODE_ERROR;
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return 0;
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}
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- while (data <= (d + n - 4)) {
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+ while ((d + n) - data >= 4) {
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n2s(data, type);
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n2s(data, size);
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- if (data + size > (d + n))
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+ if ((d + n) - data < size)
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goto ri_check;
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if (s->tlsext_debug_cb)
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@@ -3307,29 +3307,33 @@ int tls1_process_ticket(SSL *s, unsigned char *session_id, int len,
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/* Skip past DTLS cookie */
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if (SSL_IS_DTLS(s)) {
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i = *(p++);
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- p += i;
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- if (p >= limit)
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+
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+ if (limit - p <= i)
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return -1;
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+
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+ p += i;
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}
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/* Skip past cipher list */
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n2s(p, i);
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- p += i;
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- if (p >= limit)
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+ if (limit - p <= i)
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return -1;
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+ p += i;
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+
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/* Skip past compression algorithm list */
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i = *(p++);
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- p += i;
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- if (p > limit)
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+ if (limit - p < i)
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return -1;
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+ p += i;
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+
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/* Now at start of extensions */
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- if ((p + 2) >= limit)
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+ if (limit - p <= 2)
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return 0;
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n2s(p, i);
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- while ((p + 4) <= limit) {
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+ while (limit - p >= 4) {
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unsigned short type, size;
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n2s(p, type);
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n2s(p, size);
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- if (p + size > limit)
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+ if (limit - p < size)
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return 0;
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if (type == TLSEXT_TYPE_session_ticket) {
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int r;
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--
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2.8.4
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