do not mark GNU_STACK WX in ELFs generated from assembly

When generating ELF objects from assembly, gcc and clang mark the
GNU_STACK program headers as RWX by default. This is a security issue,
so we make sure it is marked only RW.

This modifies Anthony G. Basile's original patch for Linux to set
.note.GNU-stack whenever the assembler supports it. It is surprising
that any modern toolchain would enable an executable stack without an
explicit request. The number of programs that need an executable stack
is surely much smaller than the number of programs that include assembly.

1 files changed, 10 insertions, 0 deletions

diff --git a/update.sh b/update.sh
index c49f7eb..c8ec876 100755
--- a/update.sh
+++ b/update.sh
@@ -125,10 +125,20 @@ $CP crypto/compat/ui_openssl_win.c crypto/ui
 asm_src=$libssl_src/src/crypto
 gen_asm_stdout() {
         perl $asm_src/$2 $1 > $3.tmp
+        [[ $1 == "elf" ]] && cat <<-EOF >> $3.tmp
+        #if defined(HAVE_GNU_STACK)
+        .section .note.GNU-stack,"",%progbits
+        #endif
+        EOF
         $MV $3.tmp $3
 }
 gen_asm() {
         perl $asm_src/$2 $1 $3.tmp
+        [[ $1 == "elf" ]] && cat <<-EOF >> $3.tmp
+        #if defined(HAVE_GNU_STACK)
+        .section .note.GNU-stack,"",%progbits
+        #endif
+        EOF
         $MV $3.tmp $3
 }
 for abi in elf macosx; do