2023-05-24 16:40:24

by Thomas Weißschuh

Subject: [PATCH] tools/nolibc: s390: disable stackprotector in _start

s390 does not support the "global" stack protector mode that is
implemented in nolibc.

Now that nolibc detects if stack protectors are enabled at runtime it
could happen that a future compiler does indeed use global mode on
and nolibc would compile but segfault at runtime.

To avoid this hypothetic case and to align s390 with the other
architectures disable stack protectors when compiling _start().

Signed-off-by: Thomas Weißschuh <[email protected]>
---
tools/include/nolibc/arch-s390.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/include/nolibc/arch-s390.h b/tools/include/nolibc/arch-s390.h
index a738e7f3f8e8..516dff5bff8b 100644
--- a/tools/include/nolibc/arch-s390.h
+++ b/tools/include/nolibc/arch-s390.h
@@ -8,6 +8,8 @@
#include <asm/signal.h>
#include <asm/unistd.h>

+#include "compiler.h"
+
/* The struct returned by the stat() syscall, equivalent to stat64(). The
* syscall returns 116 bytes and stops in the middle of __unused.
*/
@@ -164,7 +166,7 @@ char **environ __attribute__((weak));
const unsigned long *_auxv __attribute__((weak));

/* startup code */
-void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void)
+void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) __no_stack_protector _start(void)
{
__asm__ volatile (
"lg %r2,0(%r15)\n" /* argument count */

---
base-commit: d5d0994c2f3cae2d2bdc04b98c6212e72efe0509
change-id: 20230524-nolibc-stackprotector-s390-0bc5c197ff6f

Best regards,
--
Thomas Weißschuh <[email protected]>

2023-05-24 16:42:04

by Willy Tarreau

Subject: Re: [PATCH] tools/nolibc: s390: disable stackprotector in _start

On Wed, May 24, 2023 at 06:27:06PM +0200, Thomas Wei?schuh wrote:
> s390 does not support the "global" stack protector mode that is
> implemented in nolibc.
>
> Now that nolibc detects if stack protectors are enabled at runtime it
> could happen that a future compiler does indeed use global mode on
> and nolibc would compile but segfault at runtime.
>
> To avoid this hypothetic case and to align s390 with the other
> architectures disable stack protectors when compiling _start().
(...)

Queued, same branch. Thanks Thomas!
Willy