From: kettenis <kettenis@openbsd.org>
Date: Wed, 13 Mar 2024 11:18:42 +0000 (+0000)
Subject: Add endbr64/bti instruction at the start of the gadget, otherwise we'll
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=8784bc95e0f81d168290a273cb96649cc97e4c4e;p=openbsd

Add endbr64/bti instruction at the start of the gadget, otherwise we'll
get a SIGILL when the gadget gets call.  Fix the instruction that sets
the syscall number on arm64.

ok anton@, deraadt@
---

diff --git a/regress/usr.bin/lastcomm/gadget.S b/regress/usr.bin/lastcomm/gadget.S
index dc0ca6cc8bb..8c91db6ed80 100644
--- a/regress/usr.bin/lastcomm/gadget.S
+++ b/regress/usr.bin/lastcomm/gadget.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: gadget.S,v 1.1 2023/01/09 11:50:01 anton Exp $	*/
+/*	$OpenBSD: gadget.S,v 1.2 2024/03/13 11:18:42 kettenis Exp $	*/
 
 #include <sys/syscall.h>
 #include <machine/asm.h>
@@ -12,11 +12,13 @@
         .type	gadget_getpid,_ASM_TYPE_FUNCTION
 gadget_getpid:
 #if defined(__amd64__)
+	endbr64
 	mov	$SYS_getpid, %eax
 	syscall
 	ret
 #elif defined(__aarch64__)
-	ldr	x8, #SYS_getpid
+	bti	c
+	mov	x8, #SYS_getpid
 	svc	0
 	dsb	nsh
 	isb