Add stack smash protection support.

libc/Makefile

@@ -71,10 +71,11 @@ signal/sigisemptyset.o \
 signal/sigismember.o \
 signal/signotset.o \
 signal/sigorset.o \
+ssp/__stack_chk_fail.o \
 stdio/asprintf.o \
+stdio/cbprintf.o \
 stdio/clearerr.o \
 stdio/clearerr_unlocked.o \
-stdio/cbprintf.o \
 stdio/dprintf.o \
 stdio_ext/__fbufsize.o \
 stdio_ext/__fpending.o \

libc/ssp/__stack_chk_fail.cpp

@@ -0,0 +1,64 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2014, 2015.
+
+    This file is part of the Sortix C Library.
+
+    The Sortix C Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or (at your
+    option) any later version.
+
+    The Sortix C Library is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+    or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
+
+    ssp/__stack_chk_fail.cpp
+    Abnormally terminate the process on stack smashing.
+
+*******************************************************************************/
+
+#include <errno.h>
+#include <fcntl.h>
+#include <scram.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <__/wordsize.h>
+
+#if defined(__is_sortix_kernel)
+#include <sortix/kernel/log.h>
+#include <sortix/kernel/panic.h>
+#endif
+
+#if __WORDSIZE == 32
+#define STACK_CHK_GUARD 0x01234567
+#elif __WORDSIZE == 64
+#define STACK_CHK_GUARD 0x0123456789ABCDEF
+#endif
+
+#if __STDC_HOSTED__
+/* TODO: Have this filled in by the program loader. */
+#else
+/* TODO: Have this filled in by the boot loader. */
+#endif
+extern "C" { uintptr_t __stack_chk_guard = STACK_CHK_GUARD; }
+
+extern "C" __attribute__((noreturn))
+void __stack_chk_fail(void)
+{
+#if __STDC_HOSTED__
+	scram(SCRAM_STACK_SMASH, NULL);
+#elif defined(__is_sortix_kernel)
+	Sortix::Panic("Stack smashing detected");
+#else
+	#warning "You need to implement a stack smash reporting mechanism"
+	abort();
+#endif
+}