aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--erts/emulator/beam/utils.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c
index 4dc724605b..85647b8500 100644
--- a/erts/emulator/beam/utils.c
+++ b/erts/emulator/beam/utils.c
@@ -1678,17 +1678,22 @@ make_internal_hash(Eterm term)
* the order in which keys and values are encountered.
* We therefore calculate context independent hashes for all .
* key-value pairs and then xor them together.
+ *
+ * We *do* need to use an initial seed for each pair, i.e. the
+ * hash value, so the hash value is reset for each pair with 'hash'.
+ * If we don't, no additional entropy is given to the system and the
+ * hash collision resolution in maps:from_list/1 would fail.
*/
ESTACK_PUSH(s, hash_xor_pairs);
ESTACK_PUSH(s, hash);
ESTACK_PUSH(s, HASH_MAP_TAIL);
- hash = 0;
- hash_xor_pairs = 0;
for (i = size - 1; i >= 0; i--) {
+ ESTACK_PUSH(s, hash); /* initial seed for all pairs */
ESTACK_PUSH(s, HASH_MAP_PAIR);
ESTACK_PUSH(s, vs[i]);
ESTACK_PUSH(s, ks[i]);
}
+ hash_xor_pairs = 0;
goto pop_next;
}
case HAMT_SUBTAG_HEAD_ARRAY:
@@ -1700,7 +1705,6 @@ make_internal_hash(Eterm term)
ESTACK_PUSH(s, hash_xor_pairs);
ESTACK_PUSH(s, hash);
ESTACK_PUSH(s, HASH_MAP_TAIL);
- hash = 0;
hash_xor_pairs = 0;
}
switch (hdr & _HEADER_MAP_SUBTAG_MASK) {
@@ -1717,6 +1721,7 @@ make_internal_hash(Eterm term)
while (i) {
if (is_list(*ptr)) {
Eterm* cons = list_val(*ptr);
+ ESTACK_PUSH(s, hash); /* initial seed for all pairs */
ESTACK_PUSH(s, HASH_MAP_PAIR);
ESTACK_PUSH(s, CDR(cons));
ESTACK_PUSH(s, CAR(cons));
@@ -1921,7 +1926,7 @@ make_internal_hash(Eterm term)
}
case HASH_MAP_PAIR:
hash_xor_pairs ^= hash;
- hash = 0;
+ hash = (Uint32) ESTACK_POP(s); /* initial seed for all pairs */
goto pop_next;
case HASH_CDR: