Fix possible buffer overrun.

(cherry picked from commit 2db3ea29298bdc347f15fbfab6d5746022f05101)

Conflicts:
	ssl/ssl_locl.h
	ssl/t1_lib.c

2 files changed, 20 insertions, 18 deletions

diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h
index adb1f3214b..d8248e3504 100644
--- a/ssl/ssl_locl.h
+++ b/ssl/ssl_locl.h
@@ -1264,8 +1264,8 @@ int tls1_shared_list(SSL *s,
 			const unsigned char *l1, size_t l1len,
 			const unsigned char *l2, size_t l2len,
 			int nmatch);
-unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned char *limit, int *al);
-unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *p, unsigned char *limit, int *al);
+unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *buf, unsigned char *limit, int *al);
+unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf, unsigned char *limit, int *al);
 int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **data, unsigned char *d, int n);
 int ssl_check_clienthello_tlsext_late(SSL *s);
 int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **data, unsigned char *d, int n);
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index ce144c2d73..319009df0f 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -1089,10 +1089,11 @@ void ssl_set_client_disabled(SSL *s)
 	c->valid = 1;
 	}
 
-unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned char *limit, int *al)
+unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *buf, unsigned char *limit, int *al)
 	{
 	int extdatalen=0;
-	unsigned char *ret = p;
+	unsigned char *orig = buf;
+	unsigned char *ret = buf;
 #ifndef OPENSSL_NO_EC
 	/* See if we support any ECC ciphersuites */
 	int using_ecc = 0;
@@ -1121,7 +1122,7 @@ unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned cha
 	/* don't add extensions for SSLv3 unless doing secure renegotiation */
 	if (s->client_version == SSL3_VERSION
 					&& !s->s3->send_connection_binding)
-		return p;
+		return orig;
 
 	ret+=2;
 
@@ -1170,7 +1171,7 @@ unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned cha
               return NULL;
               }
 
-          if((limit - p - 4 - el) < 0) return NULL;
+          if((limit - ret - 4 - el) < 0) return NULL;
           
           s2n(TLSEXT_TYPE_renegotiate,ret);
           s2n(el,ret);
@@ -1424,7 +1425,7 @@ unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned cha
 
                 ssl_add_clienthello_use_srtp_ext(s, 0, &el, 0);
                 
-                if((limit - p - 4 - el) < 0) return NULL;
+                if((limit - ret - 4 - el) < 0) return NULL;
 
                 s2n(TLSEXT_TYPE_use_srtp,ret);
                 s2n(el,ret);
@@ -1500,17 +1501,18 @@ unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned cha
 			}
 		}
 
-	if ((extdatalen = ret-p-2) == 0)
-		return p;
+	if ((extdatalen = ret-orig-2)== 0) 
+		return orig;
 
-	s2n(extdatalen,p);
+	s2n(extdatalen, orig);
 	return ret;
 	}
 
-unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *p, unsigned char *limit, int *al)
+unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf, unsigned char *limit, int *al)
 	{
 	int extdatalen=0;
-	unsigned char *ret = p;
+	unsigned char *orig = buf;
+	unsigned char *ret = buf;
 	size_t i;
 	custom_srv_ext_record *record;
 #ifndef OPENSSL_NO_NEXTPROTONEG
@@ -1524,7 +1526,7 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *p, unsigned cha
 #endif
 	/* don't add extensions for SSLv3, unless doing secure renegotiation */
 	if (s->version == SSL3_VERSION && !s->s3->send_connection_binding)
-		return p;
+		return orig;
 	
 	ret+=2;
 	if (ret>=limit) return NULL; /* this really never occurs, but ... */
@@ -1547,7 +1549,7 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *p, unsigned cha
               return NULL;
               }
 
-          if((limit - p - 4 - el) < 0) return NULL;
+          if((limit - ret - 4 - el) < 0) return NULL;
           
           s2n(TLSEXT_TYPE_renegotiate,ret);
           s2n(el,ret);
@@ -1628,7 +1630,7 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *p, unsigned cha
 
                 ssl_add_serverhello_use_srtp_ext(s, 0, &el, 0);
                 
-                if((limit - p - 4 - el) < 0) return NULL;
+                if((limit - ret - 4 - el) < 0) return NULL;
 
                 s2n(TLSEXT_TYPE_use_srtp,ret);
                 s2n(el,ret);
@@ -1739,10 +1741,10 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *p, unsigned cha
 		ret += len;
 		}
 
-	if ((extdatalen = ret-p-2)== 0) 
-		return p;
+	if ((extdatalen = ret-orig-2)== 0) 
+		return orig;
 
-	s2n(extdatalen,p);
+	s2n(extdatalen, orig);
 	return ret;
 	}