iemejia commented on code in PR #3858:
URL: https://github.com/apache/avro/pull/3858#discussion_r3566892952
##########
lang/c/src/map.c:
##########
@@ -109,13 +109,14 @@ int avro_raw_map_get_or_create(avro_raw_map_t *map, const
char *key,
i = map->elements.element_count;
avro_raw_map_entry_t *raw_entry =
(avro_raw_map_entry_t *)
avro_raw_array_append(&map->elements);
- raw_entry->key = avro_strdup(key);
- st_insert((st_table *) map->indices_by_key,
- (st_data_t) raw_entry->key, (st_data_t) i);
if (!raw_entry) {
- avro_str_free((char*)raw_entry->key);
+ /* avro_raw_array_append returns NULL on allocation
+ * failure; check before dereferencing it. */
return -ENOMEM;
}
+ raw_entry->key = avro_strdup(key);
+ st_insert((st_table *) map->indices_by_key,
+ (st_data_t) raw_entry->key, (st_data_t) i);
el = ((char *) raw_entry) + sizeof(avro_raw_map_entry_t);
is_new = 1;
Review Comment:
Fixed in 36b71c2b08: the key is now copied via avro_str_alloc() with an
explicit NULL check (avro_strdup() memcpy()s into its buffer without checking,
so it crashes on OOM). The entry is indexed only once the copy succeeds; on
failure the just-appended element is rolled back (element_count--), so the map
isn't left with a NULL-key entry.
##########
lang/c/tests/test_avro_4293.c:
##########
@@ -0,0 +1,484 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+/*
+ * A bytes/string value is encoded as a length prefix followed by that many
+ * bytes of data. A malicious or truncated input can declare a huge length with
+ * little or no actual data, which previously caused a correspondingly huge
+ * allocation before the shortfall was noticed. When the reader knows how many
+ * bytes remain (a memory-backed reader), the declared length must be rejected
+ * before allocating for it.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <errno.h>
+#include <avro.h>
+
+/* Portable set/unset of the collection-limit environment variable: MSVC has no
+ * setenv/unsetenv, so use _putenv_s (an empty value unsets the variable). */
+#ifdef _WIN32
+static void set_collection_limit(const char *value)
+{
+ _putenv_s("AVRO_MAX_COLLECTION_ITEMS", value);
+}
+static void unset_collection_limit(void)
+{
+ _putenv_s("AVRO_MAX_COLLECTION_ITEMS", "");
+}
+#else
+static void set_collection_limit(const char *value)
+{
+ setenv("AVRO_MAX_COLLECTION_ITEMS", value, 1);
+}
+static void unset_collection_limit(void)
+{
+ unsetenv("AVRO_MAX_COLLECTION_ITEMS");
+}
+#endif
+
+/* Decodes buf against the given schema and returns the avro_value_read rc.
+ * A non-zero rc means the read was rejected. */
+static int try_decode(avro_value_iface_t *iface, const char *buf, size_t
buf_size)
+{
+ int rc;
+ avro_value_t decoded;
+ avro_reader_t reader;
+
+ rc = avro_generic_value_new(iface, &decoded);
+ if (rc != 0) {
+ fprintf(stderr, "avro_generic_value_new failed: %s\n",
avro_strerror());
+ return -1;
+ }
+
+ reader = avro_reader_memory(buf, buf_size);
+ if (reader == NULL) {
+ fprintf(stderr, "avro_reader_memory failed\n");
+ avro_value_decref(&decoded);
+ return -1;
+ }
+
+ rc = avro_value_read(reader, &decoded);
+
+ avro_reader_free(reader);
+ avro_value_decref(&decoded);
+ return rc;
+}
+
+static int check_rejects_oversized(const char *schema_literal, const char
*label)
+{
+ avro_schema_t schema = NULL;
+ avro_value_iface_t *iface = NULL;
+ int rc;
+ int ret = EXIT_FAILURE;
+
+ /*
+ * A length prefix declaring 127 bytes (zig-zag long 254 -> varint
+ * 0xFE 0x01), followed by no data at all. The reader has 0 bytes
+ * remaining after the prefix, so a declared length of 127 must be
+ * rejected before allocating.
+ */
+ const char oversized[] = { (char) 0xFE, (char) 0x01 };
+
+ if (avro_schema_from_json_length(schema_literal, strlen(schema_literal),
+ &schema) != 0) {
+ fprintf(stderr, "%s: failed to parse schema: %s\n", label,
avro_strerror());
+ return EXIT_FAILURE;
+ }
+
+ iface = avro_generic_class_from_schema(schema);
+ if (iface == NULL) {
+ fprintf(stderr, "%s: failed to create iface\n", label);
+ avro_schema_decref(schema);
+ return EXIT_FAILURE;
+ }
+
+ rc = try_decode(iface, oversized, sizeof(oversized));
+ if (rc == 0) {
+ fprintf(stderr, "%s: FAIL - oversized length was accepted\n",
label);
+ } else if (rc != EINVAL) {
+ /* The availability checks reject with EINVAL before allocating.
+ * A different error (e.g. ENOSPC from failing to read after a
+ * large allocation) would indicate the pre-fix behavior. */
+ fprintf(stderr, "%s: FAIL - rejected with rc=%d (expected
EINVAL): %s\n",
+ label, rc, avro_strerror());
+ } else {
+ fprintf(stderr, "%s: oversized length rejected as expected:
%s\n",
+ label, avro_strerror());
+ ret = EXIT_SUCCESS;
+ }
+
+ avro_value_iface_decref(iface);
+ avro_schema_decref(schema);
+ return ret;
+}
+
+static int check_accepts_valid(void)
+{
+ avro_schema_t schema = NULL;
+ avro_value_iface_t *iface = NULL;
+ int rc;
+ int ret = EXIT_FAILURE;
+ const char *text = NULL;
+ size_t text_size = 0;
+ avro_value_t decoded;
+ avro_reader_t reader;
+
+ /* A well-formed 3-byte string "abc": length 3 (zig-zag 6 -> 0x06),
+ * then the bytes 'a','b','c'. This must still decode. */
+ const char valid[] = { 0x06, 'a', 'b', 'c' };
+
+ if (avro_schema_from_json_literal("\"string\"", &schema) != 0) {
+ fprintf(stderr, "valid: failed to parse schema: %s\n",
avro_strerror());
+ return EXIT_FAILURE;
+ }
+ iface = avro_generic_class_from_schema(schema);
+ if (iface == NULL) {
+ fprintf(stderr, "valid: failed to create iface\n");
+ avro_schema_decref(schema);
+ return EXIT_FAILURE;
+ }
+
+ if (avro_generic_value_new(iface, &decoded) != 0) {
+ avro_value_iface_decref(iface);
+ avro_schema_decref(schema);
+ return EXIT_FAILURE;
+ }
+ reader = avro_reader_memory(valid, sizeof(valid));
+ if (reader == NULL) {
+ fprintf(stderr, "valid: avro_reader_memory failed\n");
+ avro_value_decref(&decoded);
+ avro_value_iface_decref(iface);
+ avro_schema_decref(schema);
+ return EXIT_FAILURE;
+ }
+ rc = avro_value_read(reader, &decoded);
+ if (rc == 0 && avro_value_get_string(&decoded, &text, &text_size) == 0
&&
+ text_size == 4 && strcmp(text, "abc") == 0) {
+ fprintf(stderr, "valid: well-formed string decoded as
expected\n");
+ ret = EXIT_SUCCESS;
+ } else {
+ fprintf(stderr, "valid: FAIL - well-formed string did not
decode (rc=%d)\n", rc);
+ }
+
+ avro_reader_free(reader);
+ avro_value_decref(&decoded);
+ avro_value_iface_decref(iface);
+ avro_schema_decref(schema);
+ return ret;
+}
+
+/* An array of nulls: null elements occupy zero bytes, so a large declared
+ * count is legitimate and must not be rejected. */
Review Comment:
Fixed in 36b71c2b08: reworded — the comment no longer says a large
null-array count 'must not be rejected' (the zero-byte item cap does bound it);
it verifies a moderate count is not rejected by the available-bytes check.
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