From 003f455dab0204dd3f066ecdbea0470035f8181f Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Thu, 13 Apr 2023 14:31:33 -0400
Subject: [PATCH] Fix: logging: unhandled error in *_FMT macros
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Coverity reports:

1508779 Uncaught exception
If the exception is ever thrown, the program will crash.

In lttng::​sessiond::​rotation_thread::​_thread_function(): A C++ exception
is thrown but never caught (CWE-248)

The *_FMT macros, which use fmtlib, don't handle the case where
fmt::format throws. This can happen, in particular, when an invalid
format string is used.

The macros are modified to log the exception and abort.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I7f4a066b418a9d544a679f773df7e94640755f47
---
 src/common/error.cpp | 10 ++++++++++
 src/common/error.hpp | 42 ++++++++++++++++++++++++++++++++++++++----
 2 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/src/common/error.cpp b/src/common/error.cpp
index 0bb088066..cafb15f92 100644
--- a/src/common/error.cpp
+++ b/src/common/error.cpp
@@ -16,6 +16,7 @@
 #include <lttng/lttng-error.h>
 
 #include <inttypes.h>
+#include <iostream>
 #include <pthread.h>
 #include <stdlib.h>
 #include <string.h>
@@ -452,3 +453,12 @@ void lttng_abort_on_error(void)
 		abort();
 	}
 }
+
+[[noreturn]] void
+lttng::logging::details::die_formatting_exception(const char *format,
+						  const std::exception& formatting_exception)
+{
+	std::cerr << "Error occurred while formatting logging message: msg=`" << format
+		  << "`: " << formatting_exception.what();
+	abort();
+}
diff --git a/src/common/error.hpp b/src/common/error.hpp
index 7ce643411..93616718f 100644
--- a/src/common/error.hpp
+++ b/src/common/error.hpp
@@ -242,6 +242,7 @@ static inline void __lttng_print_check_abort(enum lttng_error_level type)
 /*
  * Version using GNU strerror_r, for linux with appropriate defines.
  */
+const char *error_get_str(int32_t code);
 #define PERROR(call, args...)                                                      \
 	do {                                                                       \
 		char *_perror_buf;                                                 \
@@ -251,11 +252,44 @@ static inline void __lttng_print_check_abort(enum lttng_error_level type)
 	} while (0);
 #endif
 
-#define DBG_FMT(format_str, args...)  DBG("%s", fmt::format(format_str, ##args).c_str())
-#define WARN_FMT(format_str, args...) WARN("%s", fmt::format(format_str, ##args).c_str())
-#define ERR_FMT(format_str, args...)  ERR("%s", fmt::format(format_str, ##args).c_str())
+namespace lttng {
+namespace logging {
+namespace details {
+[[noreturn]] void die_formatting_exception(const char *format,
+					   const std::exception& formatting_exception);
+} /* namespace details */
+} /* namespace logging */
+} /* namespace lttng */
 
-const char *error_get_str(int32_t code);
+#define DBG_FMT(format_str, args...)                                                              \
+	do {                                                                                      \
+		try {                                                                             \
+			DBG("%s", fmt::format(format_str, ##args).c_str());                       \
+		} catch (const std::exception& _formatting_exception) {                           \
+			lttng::logging::details::die_formatting_exception(format_str,             \
+									  _formatting_exception); \
+		}                                                                                 \
+	} while (0);
+
+#define WARN_FMT(format_str, args...)                                                             \
+	do {                                                                                      \
+		try {                                                                             \
+			WARN("%s", fmt::format(format_str, ##args).c_str());                      \
+		} catch (const std::exception& _formatting_exception) {                           \
+			lttng::logging::details::die_formatting_exception(format_str,             \
+									  _formatting_exception); \
+		}                                                                                 \
+	} while (0);
+
+#define ERR_FMT(format_str, args...)                                                              \
+	do {                                                                                      \
+		try {                                                                             \
+			ERR("%s", fmt::format(format_str, ##args).c_str());                       \
+		} catch (const std::exception& _formatting_exception) {                           \
+			lttng::logging::details::die_formatting_exception(format_str,             \
+									  _formatting_exception); \
+		}                                                                                 \
+	} while (0);
 
 /*
  * Function that format the time and return the reference of log_time.str to
-- 
2.34.1