From: Demi Marie Obenour <demiobenour@gmail.com>
Date: Thu, 8 Dec 2022 20:24:01 +0000 (-0500)
Subject: fix(auth): reject invalid padding in digests
X-Git-Tag: baikal/aarch64/sdk5.10~1^2~288^2~2
X-Git-Url: https://git.baikalelectronics.ru/?a=commitdiff_plain;h=f47547b35462571636a76b737602e827ae43bc24;p=arm-tf.git

fix(auth): reject invalid padding in digests

Digests must not have padding after the SEQUENCE or OCTET STRING.

Change-Id: Id25ab23111781f8c8a97c2c3c8edf1cc4a4384c0
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
---

diff --git a/drivers/auth/mbedtls/mbedtls_crypto.c b/drivers/auth/mbedtls/mbedtls_crypto.c
index d231179f5..178bbf5f4 100644
--- a/drivers/auth/mbedtls/mbedtls_crypto.c
+++ b/drivers/auth/mbedtls/mbedtls_crypto.c
@@ -170,12 +170,15 @@ static int verify_hash(void *data_ptr, unsigned int data_len,
 	size_t len;
 	int rc;
 
-	/* Digest info should be an MBEDTLS_ASN1_SEQUENCE */
+	/*
+	 * Digest info should be an MBEDTLS_ASN1_SEQUENCE
+	 * and consume all bytes.
+	 */
 	p = (unsigned char *)digest_info_ptr;
 	end = p + digest_info_len;
 	rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED |
 				  MBEDTLS_ASN1_SEQUENCE);
-	if (rc != 0) {
+	if (rc != 0 || ((size_t)(end - p) != len)) {
 		return CRYPTO_ERR_HASH;
 	}
 
@@ -195,9 +198,9 @@ static int verify_hash(void *data_ptr, unsigned int data_len,
 		return CRYPTO_ERR_HASH;
 	}
 
-	/* Hash should be octet string type */
+	/* Hash should be octet string type and consume all bytes */
 	rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_OCTET_STRING);
-	if (rc != 0) {
+	if ((rc != 0) || ((size_t)(end - p) != len)) {
 		return CRYPTO_ERR_HASH;
 	}