Merge remote-tracking branch 'upstream-public/pr/1452' into mbedtls-2.1-proposed
diff --git a/ChangeLog b/ChangeLog
index 0eb0702..deeaccd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -17,6 +17,8 @@
implementation allowed an offline 2^80 brute force attack on the
HMAC key of a single, uninterrupted connection (with no
resumption of the session).
+ * Fix a buffer overread in ssl_parse_server_key_exchange() that could cause
+ a crash on invalid input.
Features
* Extend PKCS#8 interface by introducing support for the entire SHA
@@ -51,6 +53,8 @@
structure. Do not assume that zeroizing a context is a correct way to
reset it. Found independently by ccli8 on Github.
* In mbedtls_entropy_free(), properly free the message digest context.
+ * Fix a possible arithmetic overflow in ssl_parse_server_key_exchange()
+ that could cause a key exchange to fail on valid data.
Changes
* Clarified the documentation of mbedtls_ssl_setup.
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 94c521d..b607fda 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -2236,10 +2236,17 @@
/*
* Read signature
*/
+ if( p > end - 2 )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
+ mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+ MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+ return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+ }
sig_len = ( p[0] << 8 ) | p[1];
p += 2;
- if( end != p + sig_len )
+ if( p != end - sig_len )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );