ctr_drbg: remove mbedtls_aes_init call from mbedtls_ctr_drbg_seed

Since 11e9310 add mbedtls_aes_init call in mbedtls_ctr_drbg_init, it
should not init aes_ctx again in mbedtls_ctr_drbg_seed.

Signed-off-by: kXuan <[email protected]>

ChangeLog.d/fix-ctr-drbg-may-free-invalid-aes-context.txt

@@ -0,0 +1,4 @@
+Bugfix
+    * Fix mbedtls_ctr_drbg_free() on an initialized but unseeded context. When
+      MBEDTLS_AES_ALT is enabled, it could call mbedtls_aes_free() on an
+      uninitialized context.

library/ctr_drbg.c

@@ -449,8 +449,6 @@ int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx,
     mbedtls_mutex_init( &ctx->mutex );
 #endif
 
-    mbedtls_aes_init( &ctx->aes_ctx );
-
     ctx->f_entropy = f_entropy;
     ctx->p_entropy = p_entropy;