From: Ondřej Surý <ondrej@sury.org>
Date: Fri, 28 Aug 2020 07:30:29 +0000 (+0200)
Subject: Fix off-by-one error when calculating new hashtable size
X-Git-Tag: v9.17.5~26^2~1
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=78543ad5a7731e5f3a309c73e90a552df1a44af1;p=thirdparty%2Fbind9.git

Fix off-by-one error when calculating new hashtable size

When calculating the new hashtable bitsize, there was an off-by-one
error that would allow the new bitsize to be larger than maximum allowed
causing assertion failure in the rehash() function.
---

diff --git a/lib/dns/rbt.c b/lib/dns/rbt.c
index aaa1acf6c7c..82c8ef77fb7 100644
--- a/lib/dns/rbt.c
+++ b/lib/dns/rbt.c
@@ -2330,10 +2330,9 @@ inithash(dns_rbt_t *rbt) {
 
 static uint32_t
 rehash_bits(dns_rbt_t *rbt, size_t newcount) {
-	uint32_t oldbits = rbt->hashbits;
-	uint32_t newbits = oldbits;
+	uint32_t newbits = rbt->hashbits;
 
-	while (newcount >= HASHSIZE(newbits) && newbits <= rbt->maxhashbits) {
+	while (newcount >= HASHSIZE(newbits) && newbits < rbt->maxhashbits) {
 		newbits += 1;
 	}
 
@@ -2380,7 +2379,7 @@ rehash(dns_rbt_t *rbt, uint32_t newbits) {
 static void
 maybe_rehash(dns_rbt_t *rbt, size_t newcount) {
 	uint32_t newbits = rehash_bits(rbt, newcount);
-	if (rbt->hashbits < newbits && newbits <= RBT_HASH_MAX_BITS) {
+	if (rbt->hashbits < newbits && newbits <= rbt->maxhashbits) {
 		rehash(rbt, newbits);
 	}
 }