Merge remote-tracking branch 'upstream-public/pr/1464' into mbedtls-2.7-proposed
diff --git a/ChangeLog b/ChangeLog
index 2c14930..362f303 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -53,6 +53,9 @@
* Verify that when (f_send, f_recv and f_recv_timeout) send or receive
more than the required length an error is returned. Raised by
Sam O'Connor in #1245.
+ * Improve robustness of mbedtls_ssl_derive_keys against the use of
+ HMAC functions with non-HMAC ciphersuites. Independently contributed
+ by Jiayuan Chen in #1377. Fixes #1437.
= mbed TLS 2.7.2 branch released 2018-03-16
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 28905c9..d386dfa 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -855,8 +855,13 @@
defined(MBEDTLS_SSL_PROTO_TLS1_2)
if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 )
{
- mbedtls_md_hmac_starts( &transform->md_ctx_enc, mac_enc, mac_key_len );
- mbedtls_md_hmac_starts( &transform->md_ctx_dec, mac_dec, mac_key_len );
+ /* For HMAC-based ciphersuites, initialize the HMAC transforms.
+ For AEAD-based ciphersuites, there is nothing to do here. */
+ if( mac_key_len != 0 )
+ {
+ mbedtls_md_hmac_starts( &transform->md_ctx_enc, mac_enc, mac_key_len );
+ mbedtls_md_hmac_starts( &transform->md_ctx_dec, mac_dec, mac_key_len );
+ }
}
else
#endif