iemejia commented on code in PR #3858:
URL: https://github.com/apache/avro/pull/3858#discussion_r3565199445
##########
lang/c/src/value-read.c:
##########
@@ -38,6 +39,79 @@ static int
read_value(avro_reader_t reader, avro_value_t *dest);
+/*
+ * Minimum number of bytes a single value of the given schema can occupy on the
+ * wire. Used to reject an array/map block count that could not be backed by
the
+ * bytes remaining. A type that can encode to zero bytes (null) returns 0,
which
+ * disables the collection check for it (so an array of nulls is not falsely
+ * rejected). A recursion guard breaks self-referencing schemas.
+ */
+static int64_t
+min_bytes_per_element(avro_schema_t schema, int depth)
+{
+ if (schema == NULL) {
+ return 0;
+ }
+ if (depth > 64) {
+ /* A cyclic or pathologically deep schema. Return 1 (not 0) so
the
+ * collection check stays enabled rather than being silently
+ * bypassed; a valid recursive value always encodes to >= 1
byte. */
+ return 1;
+ }
+ switch (avro_typeof(schema)) {
+ case AVRO_NULL:
+ return 0;
+ case AVRO_FLOAT:
+ return 4;
+ case AVRO_DOUBLE:
+ return 8;
+ case AVRO_FIXED:
+ return avro_schema_fixed_size(schema);
+ case AVRO_RECORD: {
+ size_t n = avro_schema_record_size(schema);
+ int64_t total = 0;
+ size_t i;
+ for (i = 0; i < n; i++) {
+ avro_schema_t field =
+ avro_schema_record_field_get_by_index(schema, i);
+ total += min_bytes_per_element(field, depth + 1);
+ }
Review Comment:
Fixed in b549013: the record field-minima sum now saturates to INT64_MAX
instead of overflowing, so a wrapped negative total can no longer disable the
collection check.
##########
lang/c/src/value-read.c:
##########
@@ -83,6 +164,12 @@ read_map_value(avro_reader_t reader, avro_value_t *dest)
size_t index = 0; /* index within the entire array */
int64_t block_count;
int64_t block_size;
+ int64_t min_bytes;
+ avro_schema_t map_schema = avro_value_get_schema(dest);
+
+ /* Map keys are strings (>= 1 byte length prefix) plus the value. */
+ min_bytes = 1 + min_bytes_per_element(
+ map_schema ? avro_schema_map_values(map_schema) : NULL, 0);
Review Comment:
Fixed in b549013: the map computation saturates the key's +1 (only adds when
below INT64_MAX), so a maxed-out value minimum cannot wrap.
##########
lang/c/tests/test_avro_4293.c:
##########
@@ -0,0 +1,229 @@
+/*
+ * 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>
+
+/* 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));
+ rc = avro_value_read(reader, &decoded);
Review Comment:
Fixed in b549013: check_accepts_valid() now checks avro_reader_memory() for
NULL before use.
##########
lang/c/tests/test_avro_4293.c:
##########
@@ -0,0 +1,229 @@
+/*
+ * 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>
+
+/* 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));
+ 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. */
+static int check_accepts_null_array(void)
+{
+ avro_schema_t schema = NULL;
+ avro_value_iface_t *iface = NULL;
+ avro_value_t decoded;
+ avro_reader_t reader;
+ int rc;
+ int ret = EXIT_FAILURE;
+ size_t count = 0;
+
+ /* count 127 (zig-zag 254 -> 0xFE 0x01), then the end-of-array marker
0. */
+ const char null_array[] = { (char) 0xFE, (char) 0x01, 0x00 };
+
+ if
(avro_schema_from_json_length("{\"type\":\"array\",\"items\":\"null\"}",
+
strlen("{\"type\":\"array\",\"items\":\"null\"}"),
+ &schema) != 0) {
+ fprintf(stderr, "null-array: failed to parse schema: %s\n",
avro_strerror());
+ return EXIT_FAILURE;
+ }
+ iface = avro_generic_class_from_schema(schema);
+ if (iface == NULL) {
+ 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(null_array, sizeof(null_array));
+ rc = avro_value_read(reader, &decoded);
Review Comment:
Fixed in b549013: check_accepts_null_array() now checks avro_reader_memory()
for NULL before use.
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