Merge pull request #23351 from keszybz/logind-message

logind: fix crash in logind on bad message string

src/basic/log.c

@@ -67,6 +67,10 @@ static bool prohibit_ipc = false;
  * use here. */
 static char *log_abort_msg = NULL;
 
+#if LOG_MESSAGE_VERIFICATION || defined(__COVERITY__)
+bool _log_message_dummy = false; /* Always false */
+#endif
+
 /* An assert to use in logging functions that does not call recursively
  * into our logging functions (since that might lead to a loop). */
 #define assert_raw(expr)                                                \

src/basic/log.h

@@ -298,8 +298,16 @@ int log_emergency_level(void);
 
 bool log_on_console(void) _pure_;
 
-/* Helper to prepare various field for structured logging */
-#define LOG_MESSAGE(fmt, ...) "MESSAGE=" fmt, ##__VA_ARGS__
+/* Helper to wrap the main message in structured logging. The macro doesn't do much,
+ * except to provide visual grouping of the format string and its arguments. */
+#if LOG_MESSAGE_VERIFICATION || defined(__COVERITY__)
+/* Do a fake formatting of the message string to let the scanner verify the arguments against the format
+ * message. The variable will never be set to true, but we don't tell the compiler that :) */
+extern bool _log_message_dummy;
+#  define LOG_MESSAGE(fmt, ...) "MESSAGE=%.0d" fmt, (_log_message_dummy && printf(fmt, ##__VA_ARGS__)), ##__VA_ARGS__
+#else
+#  define LOG_MESSAGE(fmt, ...) "MESSAGE=" fmt, ##__VA_ARGS__
+#endif
 
 void log_received_signal(int level, const struct signalfd_siginfo *si);
 

src/basic/user-util.c

@@ -794,7 +794,7 @@ bool valid_user_group_name(const char *u, ValidUserFlags flags) {
                 /* Compare with strict result and warn if result doesn't match */
                 if (FLAGS_SET(flags, VALID_USER_WARN) && !valid_user_group_name(u, 0))
                         log_struct(LOG_NOTICE,
-                                   "MESSAGE=Accepting user/group name '%s', which does not match strict user/group name rules.", u,
+                                   LOG_MESSAGE("Accepting user/group name '%s', which does not match strict user/group name rules.", u),
                                    "USER_GROUP_NAME=%s", u,
                                    "MESSAGE_ID=" SD_MESSAGE_UNSAFE_USER_NAME_STR);