# HG changeset patch
# User Hans Petter Jansson <hpj@cl.no>
# Date 1574234739 -3600
#      Wed Nov 20 08:25:39 2019 +0100
# Node ID 5396ffb26887cc0cd42b9f12cc6c8e3dfdaf194b
# Parent  f5cf5d16deb68e65b5dd4e799d9e8e3098400d62
[PATCH] 22
From 41dd171b242b0cb550d12760da110db7e2c21daf Mon Sep 17 00:00:00 2001
---
 nss/lib/freebl/gcm.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

Index: nss/lib/freebl/gcm.c
===================================================================
--- nss.orig/lib/freebl/gcm.c
+++ nss/lib/freebl/gcm.c
@@ -532,8 +532,14 @@ struct GCMContextStr {
     unsigned char tagKey[MAX_BLOCK_SIZE];
     PRBool ctr_context_init;
     gcmIVContext gcm_iv;
+    unsigned long long gcm_iv_bytes;
 };
 
+/* NIST SP-800-38D limits the use of GCM with a single IV to 2^39 - 256
+ * bits which translates to 2^32 - 2 128bit blocks or 2^36 - 32 bytes
+ */
+#define MAX_GCM_BYTES_PER_IV    ((1ULL << 36) - 32)
+
 SECStatus gcm_InitCounter(GCMContext *gcm, const unsigned char *iv,
                           unsigned int ivLen, unsigned int tagBits,
                           const unsigned char *aad, unsigned int aadLen);
@@ -673,6 +679,8 @@ gcm_InitCounter(GCMContext *gcm, const u
         goto loser;
     }
 
+    gcm->gcm_iv_bytes = MAX_GCM_BYTES_PER_IV;
+
     /* finally mix in the AAD data */
     rv = gcmHash_Reset(ghash, aad, aadLen);
     if (rv != SECSuccess) {
@@ -774,6 +782,13 @@ GCM_EncryptUpdate(GCMContext *gcm, unsig
         return SECFailure;
     }
 
+    /* bail out if this invocation requests processing more than what is
+     * considered to be a safe limit */
+    if (gcm->gcm_iv_bytes < (unsigned long long)inlen) {
+        PORT_SetError(SEC_ERROR_INPUT_LEN);
+        return SECFailure;
+    }
+
     tagBytes = (gcm->tagBits + (PR_BITS_PER_BYTE - 1)) / PR_BITS_PER_BYTE;
     if (UINT_MAX - inlen < tagBytes) {
         PORT_SetError(SEC_ERROR_INPUT_LEN);
@@ -802,6 +817,7 @@ GCM_EncryptUpdate(GCMContext *gcm, unsig
         *outlen = 0;
         return SECFailure;
     };
+    gcm->gcm_iv_bytes -= inlen;
     *outlen += len;
     return SECSuccess;
 }