conf: don't crash when parsing.

lh_strhash mapped nullptr to zero.  ec8c67dfbc switched CONF's use to
OPENSSL_strhash, which crashes on nullptr. But CONF depends on the
nullptr handling.

Change-Id: I131c752aa089fb99b01c9e406b6994f3a6236976
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/48385
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

crypto/CMakeLists.txt

@@ -501,6 +501,7 @@ add_executable(
   cipher_extra/cipher_test.cc
   cmac/cmac_test.cc
   compiler_test.cc
+  conf/conf_test.cc
   constant_time_test.cc
   cpu-arm-linux_test.cc
   crypto_test.cc

crypto/conf/conf.c

@@ -82,7 +82,9 @@ struct conf_st {
 #define MAX_CONF_VALUE_LENGTH 65536
 
 static uint32_t conf_value_hash(const CONF_VALUE *v) {
-  return (OPENSSL_strhash(v->section) << 2) ^ OPENSSL_strhash(v->name);
+  const uint32_t section_hash = v->section ? OPENSSL_strhash(v->section) : 0;
+  const uint32_t name_hash = v->name ? OPENSSL_strhash(v->name) : 0;
+  return (section_hash << 2) ^ name_hash;
 }
 
 static int conf_value_cmp(const CONF_VALUE *a, const CONF_VALUE *b) {

crypto/conf/conf_test.cc

@@ -0,0 +1,45 @@
+/* Copyright (c) 2021, Google Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
+#include <openssl/bio.h>
+#include <openssl/conf.h>
+
+#include <gtest/gtest.h>
+
+
+TEST(ConfTest, Parse) {
+  // Check that basic parsing works. (We strongly recommend that people don't
+  // use the [N]CONF functions.)
+
+  static const char kConf[] = R"(
+# Comment
+
+key=value
+
+[section_name]
+key=value2
+)";
+
+  bssl::UniquePtr<BIO> bio(BIO_new_mem_buf(kConf, sizeof(kConf) - 1));
+  ASSERT_TRUE(bio);
+  bssl::UniquePtr<CONF> conf(NCONF_new(nullptr));
+  ASSERT_TRUE(conf);
+  ASSERT_TRUE(NCONF_load_bio(conf.get(), bio.get(), nullptr));
+  EXPECT_TRUE(NCONF_get_section(conf.get(), "section_name"));
+  EXPECT_FALSE(NCONF_get_section(conf.get(), "other_section"));
+  // Doesn't work but should.
+  // EXPECT_STREQ(NCONF_get_string(conf.get(), nullptr, "key"), "value");
+  EXPECT_STREQ(NCONF_get_string(conf.get(), "section_name", "key"), "value2");
+  EXPECT_STREQ(NCONF_get_string(conf.get(), "other_section", "key"), nullptr);
+}

include/openssl/conf.h

@@ -100,22 +100,25 @@ OPENSSL_EXPORT void NCONF_free(CONF *conf);
 // |conf|. It returns one on success and zero on error. In the event of an
 // error, if |out_error_line| is not NULL, |*out_error_line| is set to the
 // number of the line that contained the error.
-int NCONF_load(CONF *conf, const char *filename, long *out_error_line);
+OPENSSL_EXPORT int NCONF_load(CONF *conf, const char *filename,
+                              long *out_error_line);
 
 // NCONF_load_bio acts like |NCONF_load| but reads from |bio| rather than from
 // a named file.
-int NCONF_load_bio(CONF *conf, BIO *bio, long *out_error_line);
+OPENSSL_EXPORT int NCONF_load_bio(CONF *conf, BIO *bio, long *out_error_line);
 
 // NCONF_get_section returns a stack of values for a given section in |conf|.
 // If |section| is NULL, the default section is returned. It returns NULL on
 // error.
-STACK_OF(CONF_VALUE) *NCONF_get_section(const CONF *conf, const char *section);
+OPENSSL_EXPORT STACK_OF(CONF_VALUE) *NCONF_get_section(const CONF *conf,
+                                                       const char *section);
 
 // NCONF_get_string returns the value of the key |name|, in section |section|.
 // The |section| argument may be NULL to indicate the default section. It
 // returns the value or NULL on error.
-const char *NCONF_get_string(const CONF *conf, const char *section,
-                             const char *name);
+OPENSSL_EXPORT const char *NCONF_get_string(const CONF *conf,
+                                            const char *section,
+                                            const char *name);
 
 
 // Utility functions