From f306d400c0d986dc246d74ea7916211c2bb45632 Mon Sep 17 00:00:00 2001
From: Nick Terrell <terrelln@fb.com>
Date: Mon, 21 Aug 2017 11:12:11 -0700
Subject: [PATCH] [cover] Fix divide by zero

---
 lib/dictBuilder/cover.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/lib/dictBuilder/cover.c b/lib/dictBuilder/cover.c
index 3d445ae8b..cc4b13376 100644
--- a/lib/dictBuilder/cover.c
+++ b/lib/dictBuilder/cover.c
@@ -479,11 +479,16 @@ static COVER_segment_t COVER_selectSegment(const COVER_ctx_t *ctx, U32 *freqs,
  * Check the validity of the parameters.
  * Returns non-zero if the parameters are valid and 0 otherwise.
  */
-static int COVER_checkParameters(ZDICT_cover_params_t parameters) {
+static int COVER_checkParameters(ZDICT_cover_params_t parameters,
+                                 size_t maxDictSize) {
   /* k and d are required parameters */
   if (parameters.d == 0 || parameters.k == 0) {
     return 0;
   }
+  /* k <= maxDictSize */
+  if (parameters.k > maxDictSize) {
+    return 0;
+  }
   /* d <= k */
   if (parameters.d > parameters.k) {
     return 0;
@@ -648,7 +653,7 @@ ZDICTLIB_API size_t ZDICT_trainFromBuffer_cover(
   COVER_ctx_t ctx;
   COVER_map_t activeDmers;
   /* Checks */
-  if (!COVER_checkParameters(parameters)) {
+  if (!COVER_checkParameters(parameters, dictBufferCapacity)) {
     DISPLAYLEVEL(1, "Cover parameters incorrect\n");
     return ERROR(GENERIC);
   }
@@ -995,7 +1000,7 @@ ZDICTLIB_API size_t ZDICT_optimizeTrainFromBuffer_cover(
       data->parameters.d = d;
       data->parameters.steps = kSteps;
       /* Check the parameters */
-      if (!COVER_checkParameters(data->parameters)) {
+      if (!COVER_checkParameters(data->parameters, dictBufferCapacity)) {
         DISPLAYLEVEL(1, "Cover parameters incorrect\n");
         free(data);
         continue;