From 2f660d047dd60ac68ebe6c8d4da0d141403b6d71 Mon Sep 17 00:00:00 2001
From: Hanno Becker <hanno.becker@arm.com>
Date: Tue, 18 Dec 2018 17:04:59 +0000
Subject: [PATCH] Forbid passing NULL input buffers to RSA encryption routines

---
 include/mbedtls/rsa.h | 9 +++------
 library/rsa.c         | 6 +++---
 2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/include/mbedtls/rsa.h b/include/mbedtls/rsa.h
index 5171fc971..bec74a9ce 100644
--- a/include/mbedtls/rsa.h
+++ b/include/mbedtls/rsa.h
@@ -601,8 +601,7 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx,
  *                 #MBEDTLS_RSA_PUBLIC or #MBEDTLS_RSA_PRIVATE (deprecated).
  * \param ilen     The length of the plaintext in Bytes.
  * \param input    The input data to encrypt. This must be a readable
- *                 buffer of size \p ilen Bytes. It may be \c NULL if
- *                 `ilen == 0`.
+ *                 buffer of size \p ilen Bytes. This must not be \c NULL.
  * \param output   The output buffer. This must be a writable buffer
  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
  *                 for an 2048-bit RSA modulus.
@@ -642,8 +641,7 @@ int mbedtls_rsa_pkcs1_encrypt( mbedtls_rsa_context *ctx,
  *                 #MBEDTLS_RSA_PUBLIC or #MBEDTLS_RSA_PRIVATE (deprecated).
  * \param ilen     The length of the plaintext in Bytes.
  * \param input    The input data to encrypt. This must be a readable
- *                 buffer of size \p ilen Bytes. It may be \c NULL if
- *                 `ilen == 0`.
+ *                 buffer of size \p ilen Bytes. This must not be \c NULL.
  * \param output   The output buffer. This must be a writable buffer
  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
  *                 for an 2048-bit RSA modulus.
@@ -687,8 +685,7 @@ int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx,
  * \param label_len  The length of the label in Bytes.
  * \param ilen       The length of the plaintext buffer \p input in Bytes.
  * \param input      The input data to encrypt. This must be a readable
- *                   buffer of size \p ilen Bytes. It may be \c NULL if
- *                   `ilen == 0`.
+ *                   buffer of size \p ilen Bytes. This must not be \c NULL.
  * \param output     The output buffer. This must be a writable buffer
  *                   of length \c ctx->len Bytes. For example, \c 256 Bytes
  *                   for an 2048-bit RSA modulus.
diff --git a/library/rsa.c b/library/rsa.c
index 154738ff7..86bec64c9 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -1135,7 +1135,7 @@ int mbedtls_rsa_rsaes_oaep_encrypt( mbedtls_rsa_context *ctx,
     RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
                       mode == MBEDTLS_RSA_PUBLIC );
     RSA_VALIDATE_RET( output != NULL );
-    RSA_VALIDATE_RET( ilen == 0 || input != NULL );
+    RSA_VALIDATE_RET( input != NULL );
     RSA_VALIDATE_RET( label_len == 0 || label != NULL );
 
     if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 )
@@ -1218,7 +1218,7 @@ int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx,
     RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
                       mode == MBEDTLS_RSA_PUBLIC );
     RSA_VALIDATE_RET( output != NULL );
-    RSA_VALIDATE_RET( ilen == 0 || input != NULL );
+    RSA_VALIDATE_RET( input != NULL );
 
     if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
         return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
@@ -1285,7 +1285,7 @@ int mbedtls_rsa_pkcs1_encrypt( mbedtls_rsa_context *ctx,
     RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
                       mode == MBEDTLS_RSA_PUBLIC );
     RSA_VALIDATE_RET( output != NULL );
-    RSA_VALIDATE_RET( ilen == 0 || input != NULL );
+    RSA_VALIDATE_RET( input != NULL );
 
     switch( ctx->padding )
     {