From: Taylor R Campbell <campbell@mumble.net>
Date: Sat, 17 Apr 2010 06:10:44 +0000 (-0400)
Subject: Under Linux/ELF on i386 and x86-64, mark the stack nonexecutable.
X-Git-Tag: 20100708-Gtk~69
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=a24dc2c558df3e3b67e15adf02e4fcc2e0c9ce9d;p=mit-scheme.git

Under Linux/ELF on i386 and x86-64, mark the stack nonexecutable.

This is apparently what a `.note.GNU-stack' section does.
---

diff --git a/src/microcode/cmpauxmd/i386.m4 b/src/microcode/cmpauxmd/i386.m4
index d7024e7ce..c1c61e0d9 100644
--- a/src/microcode/cmpauxmd/i386.m4
+++ b/src/microcode/cmpauxmd/i386.m4
@@ -1164,6 +1164,12 @@ asm_fixnum_rsh_overflow_negative:
 
 IFDASM(`end')
 
+# Mark the stack nonexecutable.  If we ever put code (e.g.,
+# dynamic-extent closure entry points) on the stack, this would have
+# to change.
+
+ifdef(`__linux__', `ifdef(`__ELF__', `.section .note.GNU-stack,"",%progbits')')
+
 ### Edwin Variables:
 ### comment-column: 56
 ### End:
diff --git a/src/microcode/cmpauxmd/x86-64.m4 b/src/microcode/cmpauxmd/x86-64.m4
index ee9fae39d..5524b9a11 100644
--- a/src/microcode/cmpauxmd/x86-64.m4
+++ b/src/microcode/cmpauxmd/x86-64.m4
@@ -909,6 +909,12 @@ asm_fixnum_rsh_overflow_negative:
 
 IFDASM(`end')
 
+# Mark the stack nonexecutable.  If we ever put code (e.g.,
+# dynamic-extent closure entry points) on the stack, this would have
+# to change.
+
+ifdef(`__linux__', `ifdef(`__ELF__', `.section .note.GNU-stack,"",%progbits')')
+
 ### Edwin Variables:
 ### comment-column: 56
 ### comment-start: "#"
diff --git a/src/microcode/configure.ac b/src/microcode/configure.ac
index 3f171d6e1..205b4e582 100644
--- a/src/microcode/configure.ac
+++ b/src/microcode/configure.ac
@@ -286,6 +286,7 @@ DO_GCC_TESTS=no
 GNU_LD=no
 case ${host_os} in
 linux-gnu)
+    M4_FLAGS="${M4_FLAGS} -P __linux__,1"
     DO_GCC_TESTS=yes
     GNU_LD=yes
     ;;
@@ -387,6 +388,7 @@ if test "${DO_GCC_TESTS}" = yes; then
 	[
 	AC_MSG_RESULT([yes])
 	M4_FLAGS="${M4_FLAGS} -P SUPPRESS_LEADING_UNDERSCORE,1"
+	M4_FLAGS="${M4_FLAGS} -P __ELF__,1"
 	],
 	[AC_MSG_RESULT([no])])
 fi