Check for valid stack frame in longjmp.

If longjmp restores the stack frame to an address which is beyond
the stack frame at the time of the longjmp call it would install
an uninitialized stack frame.  If compiled with _FORTIFY_SOURCE
defined, longjmp will now bail out in this situation.

ChangeLog

@@ -1,5 +1,24 @@
 2009-05-15  Ulrich Drepper  <drepper@redhat.com>
 
+	* Versions.def: Add GLIBC_2.11 for libc.
+	* debug/Makefile (routines): Add longjmp_chk.
+	Add rules to build and run tst-longjmp_chk.
+	* debug/Versions: Export __longjmp_chk for GLIBC_2.11.
+	* debug/longjmp_chk.c: New file.
+	* debug/tst-longjmp_chk.c: New file.
+	* include/bits/setjmp2.: New file.
+	* include/stdio.h: Mark __fortify_fail as internal_function.
+	* setjmp/Makefile (headers): Add bits/setjmp2.h.
+	* setjmp/bits/setjmp2.h: New file.
+	* setjmp/longjmp.c: If __libc_siglongjmp is defined, don't define any
+	of the aliases.
+	* setjmp/setjmp.h: Include <bits/setjmp2.h> if _FORTIFY_SOURCE is
+	defined.
+	* sysdeps/i386/____longjmp_chk.S: New file.
+	* sysdeps/x86_64/____longjmp_chk.S: New file.
+	* sysdeps/i386/__longjmp.S: If CHECK_ESP is defined, use it.
+	* sysdeps/x86_64/__longjmp.S: Likewise.
+
 	* version.h: Bump for 2.11 development.
 
 	* elf/check-execstack.c: New file.

NEWS

@@ -1,9 +1,15 @@
-GNU C Library NEWS -- history of user-visible changes.  2009-4-23
+GNU C Library NEWS -- history of user-visible changes.  2009-5-15
 Copyright (C) 1992-2008, 2009 Free Software Foundation, Inc.
 See the end for copying conditions.
 
 Please send GNU C library bug reports via <http://sources.redhat.com/bugzilla/>
 using `glibc' in the "product" field.
+
+Version 2.11
+
+* checking version of longjmp added that fails if an uninitialized stack
+  frame would be created.  Implemented by Ulrich Drepper.
+
 
 Version 2.10
 

Versions.def

@@ -27,6 +27,7 @@ libc {
   GLIBC_2.8
   GLIBC_2.9
   GLIBC_2.10
+  GLIBC_2.11
 %ifdef USE_IN_LIBIO
   HURD_CTHREADS_0.3
 %endif

debug/Makefile

@@ -1,4 +1,4 @@
-# Copyright (C) 1998-2001,2004-2008 Free Software Foundation, Inc.
+# Copyright (C) 1998-2001,2004-2008, 2009 Free Software Foundation, Inc.
 # This file is part of the GNU C Library.
 
 # The GNU C Library is free software; you can redistribute it and/or
@@ -43,6 +43,7 @@ routines  = backtrace backtracesyms backtracesymsfd noophooks \
 	    wcsnrtombs_chk mbsrtowcs_chk wcsrtombs_chk mbstowcs_chk \
 	    wcstombs_chk asprintf_chk vasprintf_chk dprintf_chk \
 	    vdprintf_chk obprintf_chk \
+	    longjmp_chk ____longjmp_chk \
 	    stack_chk_fail fortify_fail \
 	    $(static-only-routines)
 static-only-routines := warning-nop stack_chk_fail_local
@@ -79,6 +80,8 @@ CFLAGS-pread_chk.c = -fexceptions -fasynchronous-unwind-tables
 CFLAGS-pread64_chk.c = -fexceptions -fasynchronous-unwind-tables
 CFLAGS-recv_chk.c = -fexceptions -fasynchronous-unwind-tables
 CFLAGS-recvfrom_chk.c = -fexceptions -fasynchronous-unwind-tables
+CFLAGS-tst-longjmp_chk.c = -fexceptions -fasynchronous-unwind-tables \
+			   -D_FORTIFY_SOURCE=1
 
 # We know these tests have problems with format strings, this is what
 # we are testing.  Disable that warning.
@@ -113,7 +116,7 @@ LDFLAGS-tst-lfschk4 = -lstdc++
 LDFLAGS-tst-lfschk5 = -lstdc++
 LDFLAGS-tst-lfschk6 = -lstdc++
 
-tests = backtrace-tst tst-chk1 tst-chk2 tst-chk3 \
+tests = backtrace-tst tst-longjmp_chk tst-chk1 tst-chk2 tst-chk3 \
 	tst-lfschk1 tst-lfschk2 tst-lfschk3 test-strcpy_chk test-stpcpy_chk \
 	tst-chk4 tst-chk5 tst-chk6 tst-lfschk4 tst-lfschk5 tst-lfschk6
 

debug/Versions

@@ -46,6 +46,9 @@ libc {
     __asprintf_chk; __vasprintf_chk;  __dprintf_chk; __vdprintf_chk;
     __obstack_printf_chk; __obstack_vprintf_chk;
   }
+  GLIBC_2.11 {
+    __longjmp_chk;
+  }
   GLIBC_PRIVATE {
     __fortify_fail;
   }

debug/longjmp_chk.c

@@ -0,0 +1,28 @@
+/* Copyright (C) 2009 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU 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 2.1 of the License, or (at your option) any later version.
+
+   The GNU 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 GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <setjmp.h>
+
+// XXX Should move to include/setjmp.h
+extern void ____longjmp_chk (__jmp_buf __env, int __val)
+     __attribute__ ((__noreturn__));
+
+#define __longjmp ____longjmp_chk
+#define __libc_siglongjmp __longjmp_chk
+
+#include <setjmp/longjmp.c>

debug/tst-longjmp_chk.c

@@ -0,0 +1,86 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <paths.h>
+#include <setjmp.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static jmp_buf b;
+
+
+static void
+__attribute__ ((noinline))
+f (void)
+{
+  char buf[1000];
+  asm volatile ("" : "=m" (buf));
+
+  if (setjmp (b) != 0)
+    {
+      puts ("second longjmp succeeded");
+      exit (1);
+    }
+}
+
+
+static bool expected_to_fail;
+
+
+static void
+handler (int sig)
+{
+  if (expected_to_fail)
+    _exit (0);
+  else
+    {
+      static const char msg[] = "unexpected longjmp failure\n";
+      TEMP_FAILURE_RETRY (write (STDOUT_FILENO, msg, sizeof (msg) - 1));
+      _exit (1);
+    }
+}
+
+
+int
+main (void)
+{
+  struct sigaction sa;
+  sa.sa_handler = handler;
+  sa.sa_flags = 0;
+  sigemptyset (&sa.sa_mask);
+
+  sigaction (SIGABRT, &sa, NULL);
+
+  /* Avoid all the buffer overflow messages on stderr.  */
+  int fd = open (_PATH_DEVNULL, O_WRONLY);
+  if (fd == -1)
+    close (STDERR_FILENO);
+  else
+    {
+      dup2 (fd, STDERR_FILENO);
+      close (fd);
+    }
+  setenv ("LIBC_FATAL_STDERR_", "1", 1);
+
+
+  expected_to_fail = false;
+
+  if (setjmp (b) == 0)
+    {
+      longjmp (b, 1);
+      /* NOTREACHED */
+      printf ("first longjmp returned\n");
+      return 1;
+    }
+
+
+  expected_to_fail = true;
+
+  f ();
+  longjmp (b, 1);
+
+  puts ("second longjmp returned");
+  return 1;
+}

include/bits/setjmp2.h

@@ -0,0 +1 @@
+#include <setjmp/bits/setjmp2.h>

include/stdio.h

@@ -90,7 +90,8 @@ extern int __gen_tempname (char *__tmpl, int __flags, int __kind);
 extern void __libc_fatal (__const char *__message)
      __attribute__ ((__noreturn__));
 extern void __libc_message (int do_abort, __const char *__fnt, ...);
-extern void __fortify_fail (const char *msg) __attribute__ ((noreturn));
+extern void __fortify_fail (const char *msg)
+     __attribute__ ((__noreturn__)) internal_function;
 libc_hidden_proto (__fortify_fail)
 
 /* Acquire ownership of STREAM.  */

setjmp/Makefile

@@ -1,4 +1,4 @@
-# Copyright (C) 1991, 92, 93, 94, 95, 97 Free Software Foundation, Inc.
+# Copyright (C) 1991, 92, 93, 94, 95, 97, 2009 Free Software Foundation, Inc.
 # This file is part of the GNU C Library.
 
 # The GNU C Library is free software; you can redistribute it and/or
@@ -21,7 +21,7 @@
 #
 subdir	:= setjmp
 
-headers	:= setjmp.h bits/setjmp.h
+headers	:= setjmp.h bits/setjmp.h bits/setjmp2.h
 
 routines	:= setjmp sigjmp bsd-setjmp bsd-_setjmp \
 		   longjmp __longjmp jmp-unwind

setjmp/bits/setjmp2.h

@@ -0,0 +1,41 @@
+/* Checking macros for setjmp functions.
+ * Copyright (C) 2009 Free Software Foundation, Inc.
+ * This file is part of the GNU C Library.
+ *
+ * The GNU 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 2.1 of the License, or (at your option) any later version.
+ *
+ * The GNU 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 GNU C Library; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA.  */
+
+#ifndef _SETJMP_H
+# error "Never include <bits/setjmp2.h> directly; use <setjmp.h> instead."
+#endif
+
+/* Variant of the longjmp functions which perform some sanity checking.  */
+#ifdef __REDIRECT_NTH
+extern void __REDIRECT_NTH (longjmp,
+			    (struct __jmp_buf_tag __env[1], int __val),
+			    __longjmp_chk) __attribute__ ((__noreturn__));
+extern void __REDIRECT_NTH (_longjmp,
+			    (struct __jmp_buf_tag __env[1], int __val),
+			    __longjmp_chk) __attribute__ ((__noreturn__));
+extern void __REDIRECT_NTH (siglongjmp,
+			    (struct __jmp_buf_tag __env[1], int __val),
+			    __longjmp_chk) __attribute__ ((__noreturn__));
+#else
+extern void __longjmp_chk (struct __jmp_buf_tag __env[1], int __val),
+     __THROW __attribute__ ((__noreturn__));
+# define longjmp __longjmp_chk
+# define _longjmp __longjmp_chk
+# define siglongjmp __longjmp_chk
+#endif

setjmp/longjmp.c

@@ -1,4 +1,5 @@
-/* Copyright (C) 1991,92,94,95,97,98,2000,2002 Free Software Foundation, Inc.
+/* Copyright (C) 1991,92,94,95,97,98,2000,2002,2009
+   Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -39,8 +40,10 @@ __libc_siglongjmp (sigjmp_buf env, int val)
   __longjmp (env[0].__jmpbuf, val ?: 1);
 }
 
+#ifndef __libc_siglongjmp
 strong_alias (__libc_siglongjmp, __libc_longjmp)
 libc_hidden_def (__libc_longjmp)
 weak_alias (__libc_siglongjmp, _longjmp)
 weak_alias (__libc_siglongjmp, longjmp)
 weak_alias (__libc_siglongjmp, siglongjmp)
+#endif

setjmp/setjmp.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 1991-1999, 2001, 2002, 2007 Free Software Foundation, Inc.
+/* Copyright (C) 1991-1999,2001,2002,2007,2009 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -111,6 +111,12 @@ extern void siglongjmp (sigjmp_buf __env, int __val)
      __THROW __attribute__ ((__noreturn__));
 #endif /* Use POSIX.  */
 
+
+/* Define helper functions to catch unsafe code.  */
+#if __USE_FORTIFY_LEVEL > 0
+# include <bits/setjmp2.h>
+#endif
+
 __END_DECLS
 
 #endif /* setjmp.h  */

sysdeps/i386/____longjmp_chk.S

@@ -0,0 +1,45 @@
+/* Copyright (C) 2001,2004,2005,2006,2009 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU 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 2.1 of the License, or (at your option) any later version.
+
+   The GNU 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 GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+	.section .rodata.str1.1,"aMS",@progbits,1
+	.type	longjmp_msg,@object
+longjmp_msg:
+	.string "longjmp causes uninitialized stack frame"
+	.size	longjmp_msg, .-longjmp_msg
+
+
+#define __longjmp ____longjmp_chk
+
+#ifdef PIC
+# define CALL_FAIL	movl	%ebx, %ecx;				      \
+			cfi_register(%ebx,%ecx);			      \
+			LOAD_PIC_REG (bx);				      \
+			leal	longjmp_msg@GOTOFF(%ebx), %eax;		      \
+			call	__GI___fortify_fail@PLT
+#else
+# define CALL_FAIL	movl	$longjmp_msg, %eax;			      \
+			call	__fortify_fail
+#endif
+
+#define CHECK_ESP(reg) \
+	cmpl	reg, %esp;						      \
+	jbe	.Lok;							      \
+	CALL_FAIL;							      \
+.Lok:
+
+#include "__longjmp.S"

sysdeps/i386/__longjmp.S

@@ -1,5 +1,6 @@
 /* longjmp for i386.
-   Copyright (C) 1995-1998,2000,2002,2005, 2006 Free Software Foundation, Inc.
+   Copyright (C) 1995-1998,2000,2002,2005,2006,2009
+   Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -40,6 +41,9 @@ ENTRY (BP_SYM (__longjmp))
 	movl (JB_SP*4)(%eax), %ecx
 	PTR_DEMANGLE (%edx)
 	PTR_DEMANGLE (%ecx)
+# ifdef CHECK_ESP
+	CHECK_ESP (%ecx)
+# endif
 	cfi_def_cfa(%eax, 0)
 	cfi_register(%eip, %edx)
 	cfi_register(%esp, %ecx)
@@ -63,6 +67,11 @@ ENTRY (BP_SYM (__longjmp))
 	movl JBUF(%esp), %ecx	/* User's jmp_buf in %ecx.  */
 	CHECK_BOUNDS_BOTH_WIDE (%ecx, JBUF(%esp), $JB_SIZE)
 
+# ifdef CHECK_ESP
+	movl (JB_SP*4)(%ecx), %eax
+	CHECK_ESP (%eax)
+# endif
+
 	movl VAL(%esp), %eax	/* Second argument is return value.  */
 	/* Save the return address now.  */
 	movl (JB_PC*4)(%ecx), %edx