From a4b90be9fcd5e1668ac941cabce3b1ab38dbe326 Mon Sep 17 00:00:00 2001

From: antirez <antirez@gmail.com>

Date: Fri, 15 Mar 2019 17:10:16 +0100

Subject: [PATCH] HyperLogLog: enlarge reghisto variable for safety.

---

 src/hyperloglog.c | 7 ++++++-

 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/hyperloglog.c b/src/hyperloglog.c

index e993bf26e1d..526510b43b9 100644

--- a/src/hyperloglog.c

+++ b/src/hyperloglog.c

@@ -1017,7 +1017,12 @@ uint64_t hllCount(struct hllhdr *hdr, int *invalid) {

     double m = HLL_REGISTERS;

     double E;

     int j;

-    int reghisto[HLL_Q+2] = {0};

+    /* Note that reghisto could be just HLL_Q+1, becuase this is the

+     * maximum frequency of the "000...1" sequence the hash function is

+     * able to return. However it is slow to check for sanity of the

+     * input: instead we history array at a safe size: overflows will

+     * just write data to wrong, but correctly allocated, places. */

+    int reghisto[64] = {0};

     /* Compute register histogram */

     if (hdr->encoding == HLL_DENSE) {