[PATCH] i386/x86-64: Don't randomize stack top when no randomization personality is set

Based on patch from Frank van Maarseveen <frankvm@frankvm.com>, but
extended.

Signed-off-by: Andi Kleen <ak@suse.de>

arch/i386/kernel/process.c

@@ -37,6 +37,7 @@
 #include <linux/kallsyms.h>
 #include <linux/ptrace.h>
 #include <linux/random.h>
+#include <linux/personality.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -905,7 +906,7 @@ asmlinkage int sys_get_thread_area(struct user_desc __user *u_info)
 
 unsigned long arch_align_stack(unsigned long sp)
 {
-	if (randomize_va_space)
+	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 		sp -= get_random_int() % 8192;
 	return sp & ~0xf;
 }

arch/x86_64/kernel/process.c

@@ -845,7 +845,7 @@ int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
 
 unsigned long arch_align_stack(unsigned long sp)
 {
-	if (randomize_va_space)
+	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 		sp -= get_random_int() % 8192;
 	return sp & ~0xf;
 }

fs/binfmt_elf.c

@@ -515,7 +515,8 @@ static unsigned long randomize_stack_top(unsigned long stack_top)
 {
 	unsigned int random_variable = 0;
 
-	if (current->flags & PF_RANDOMIZE) {
+	if ((current->flags & PF_RANDOMIZE) &&
+		!(current->personality & ADDR_NO_RANDOMIZE)) {
 		random_variable = get_random_int() & STACK_RND_MASK;
 		random_variable <<= PAGE_SHIFT;
 	}