Jean writes:

Hello,

under some circumstances the following small example prints lots of
garbage onto the console and into the syslog:

#include <syslog.h>
int main ()
{
        openlog("foo", LOG_CONS|LOG_NDELAY|LOG_PID|LOG_PERROR, LOG_DAEMON);
        syslog (LOG_WARNING, "mlock: %m");
        return 1;
}

The reason is, that sprintf returns with -1 and vsyslog dumps the
complete buffer onto stderr and the syslogd socket. The following
patch would fix the problem:

libc/misc/syslog/syslog.c

@@ -206,7 +206,15 @@ vsyslog( int pri, const char *fmt, va_list ap )
 		memmove(head_end + sizeof(truncate_msg), head_end,
 			end - head_end - sizeof(truncate_msg));
 		memcpy(head_end, truncate_msg, sizeof(truncate_msg));
-		p = end - 1;
+		if (p < head_end) {
+			while (p < end && *p) {
+				p++;
+			}
+		}
+		else {
+			p = end - 1;
+		}
+
 	}
 	last_chr = p;