Fix crash with DTLS_CONNECTION_ID but not other SSL features

In configurations with MBEDTLS_SSL_DTLS_CONNECTION_ID enabled but none of MBEDTLS_SSL_HW_RECORD_ACCEL, MBEDTLS_SSL_EXPORT_KEYS or MBEDTLS_DEBUG_C, DTLS handshakes using CID would crash due to a null pointer dereference. Fix this. Fixes Mbed-TLS#3998. Detected by running compat.sh in config-ccm-psk-dtls1_2.h. Signed-off-by: Gilles Peskine <[email protected]>
gilles-peskine-arm · Apr 13, 2022 · a6f99a1 · a6f99a1
1 parent bcb2ab0
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diff --git a/ChangeLog.d/dtls-cid-null.txt b/ChangeLog.d/dtls-cid-null.txt
@@ -0,0 +1,5 @@
+Bugfix
+   * In configurations with MBEDTLS_SSL_DTLS_CONNECTION_ID enabled but none of
+     MBEDTLS_SSL_HW_RECORD_ACCEL, MBEDTLS_SSL_EXPORT_KEYS or MBEDTLS_DEBUG_C,
+     DTLS handshakes using CID would crash due to a null pointer dereference.
+     Fix this. Fixes #3998.
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
@@ -990,6 +990,7 @@ static int ssl_populate_transform( mbedtls_ssl_transform *transform,
 
 #if !defined(MBEDTLS_SSL_HW_RECORD_ACCEL) && \
     !defined(MBEDTLS_SSL_EXPORT_KEYS) && \
+    !defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \
     !defined(MBEDTLS_DEBUG_C)
     ssl = NULL; /* make sure we don't use it except for those cases */
     (void) ssl;