From 7b938b4d14aed5375745b8c72789afabfad4df25 Mon Sep 17 00:00:00 2001
From: Max Kellermann <mk@cm4all.com>
Date: Tue, 18 Jun 2024 17:20:06 +0200
Subject: [PATCH] util/Exception: sanitize message strings
This should prevent leaking unsanitized strings from libraries.
---
src/util/Exception.cxx | 38 ++++++++++++++++++++++++++++++++++---
test/util/TestException.cxx | 18 ++++++++++++++++++
2 files changed, 53 insertions(+), 3 deletions(-)
diff --git a/src/util/Exception.cxx b/src/util/Exception.cxx
index 351d5b7f5..17eff34df 100644
--- a/src/util/Exception.cxx
+++ b/src/util/Exception.cxx
@@ -2,9 +2,40 @@
// author: Max Kellermann <max.kellermann@gmail.com>
#include "Exception.hxx"
+#include "CharUtil.hxx"
+#include "StringStrip.hxx"
#include <utility>
+/**
+ * Append the given C string to a std::string, with some
+ * sanitizations: strip whitespace at the beginning and the end and
+ * combine multiple whitespace to a single space.
+ *
+ * This shall compress strangely formatted multi-line messages (which
+ * may come from third-party libraries) to a single line.
+ */
+static void
+AppendSanitize(std::string &dest, const char *src) noexcept
+{
+ src = StripLeft(src);
+
+ bool space = false;
+ while (char ch = *src++) {
+ if (IsWhitespaceFast(ch)) {
+ space = true;
+ continue;
+ }
+
+ if (space) {
+ space = false;
+ dest.push_back(' ');
+ }
+
+ dest.push_back(ch);
+ }
+}
+
template<typename T>
static void
AppendNestedMessage(std::string &result, T &&e,
@@ -14,13 +45,13 @@ AppendNestedMessage(std::string &result, T &&e,
std::rethrow_if_nested(std::forward<T>(e));
} catch (const std::exception &nested) {
result += separator;
- result += nested.what();
+ AppendSanitize(result, nested.what());
AppendNestedMessage(result, nested, fallback, separator);
} catch (const std::nested_exception &ne) {
AppendNestedMessage(result, ne, fallback, separator);
} catch (const char *s) {
result += separator;
- result += s;
+ AppendSanitize(result, s);
} catch (...) {
result += separator;
result += fallback;
@@ -31,7 +62,8 @@ std::string
GetFullMessage(const std::exception &e,
const char *fallback, const char *separator) noexcept
{
- std::string result = e.what();
+ std::string result;
+ AppendSanitize(result, e.what());
AppendNestedMessage(result, e, fallback, separator);
return result;
}
diff --git a/test/util/TestException.cxx b/test/util/TestException.cxx
index c5dda7fd5..6e3e706e5 100644
--- a/test/util/TestException.cxx
+++ b/test/util/TestException.cxx
@@ -6,6 +6,8 @@
#include <gtest/gtest.h>
+using std::string_view_literals::operator""sv;
+
TEST(ExceptionTest, RuntimeError)
{
ASSERT_EQ(GetFullMessage(std::make_exception_ptr(std::runtime_error("Foo"))), "Foo");
@@ -22,6 +24,22 @@ TEST(ExceptionTest, DerivedError)
ASSERT_EQ(GetFullMessage(std::make_exception_ptr(DerivedError("Foo"))), "Foo");
}
+TEST(ExceptionTest, GetFullMessageSanitize)
+{
+ try {
+ try {
+ throw " ABC \n DEF ";
+ } catch (...) {
+ std::throw_with_nested(std::runtime_error{"foo\r\n\tbar"});
+ }
+
+ FAIL();
+ } catch (...) {
+ ASSERT_EQ(GetFullMessage(std::current_exception()),
+ "foo bar; ABC DEF"sv);
+ }
+}
+
TEST(ExceptionTest, FindNestedDirect)
{
struct Foo {};