From d860e0f18b19770a2496189be1a78dab4450e841 Mon Sep 17 00:00:00 2001
From: Gabor Mezei <gabor.mezei@arm.com>
Date: Tue, 15 Feb 2022 16:02:59 +0100
Subject: [PATCH] Add comment

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
---
 library/ssl_tls13_keys.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index 25a1b5086..d135afc86 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -167,6 +167,8 @@ psa_status_t mbedtls_psa_hkdf_extract( psa_algorithm_t alg,
             return( PSA_ERROR_INVALID_ARGUMENT );
         }
 
+        /* salt_len <= sizeof( salt ) because
+           PSA_HASH_LENGTH( alg ) <= PSA_MAC_MAX_SIZE. */
         salt = null_salt;
         salt_len = hash_len;
     }