From da85df9f32b4d5351cd413963c193c3fd8a1c56e Mon Sep 17 00:00:00 2001
From: Andi Kleen <ak@suse.de>
Date: Sat, 25 Mar 2006 16:29:09 +0100
Subject: [PATCH] --- yaml --- r: 23793 b: refs/heads/master c:
 913bd906019514579b3c7ec5ab9c463e89207a57 h: refs/heads/master i:   23791:
 c4aeae3bdf203c0749fbb79d3b9601c538fe123b v: v3

---
 [refs]                         |  2 +-
 trunk/fs/binfmt_elf.c          | 13 +++++++++----
 trunk/include/asm-x86_64/elf.h |  4 ++++
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/[refs] b/[refs]
index 6d6e4197ac9a..40f23508dce5 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: dca99a38bccceda9e079d4c95abefbd9028605fe
+refs/heads/master: 913bd906019514579b3c7ec5ab9c463e89207a57
diff --git a/trunk/fs/binfmt_elf.c b/trunk/fs/binfmt_elf.c
index 4349113881fb..537893a16014 100644
--- a/trunk/fs/binfmt_elf.c
+++ b/trunk/fs/binfmt_elf.c
@@ -500,17 +500,22 @@ static unsigned long load_aout_interp(struct exec * interp_ex,
 #define INTERPRETER_AOUT 1
 #define INTERPRETER_ELF 2
 
+#ifndef STACK_RND_MASK
+#define STACK_RND_MASK 0x7ff		/* with 4K pages 8MB of VA */
+#endif
 
 static unsigned long randomize_stack_top(unsigned long stack_top)
 {
 	unsigned int random_variable = 0;
 
-	if (current->flags & PF_RANDOMIZE)
-		random_variable = get_random_int() % (8*1024*1024);
+	if (current->flags & PF_RANDOMIZE) {
+		random_variable = get_random_int() & STACK_RND_MASK;
+		random_variable <<= PAGE_SHIFT;
+	}
 #ifdef CONFIG_STACK_GROWSUP
-	return PAGE_ALIGN(stack_top + random_variable);
+	return PAGE_ALIGN(stack_top) + random_variable;
 #else
-	return PAGE_ALIGN(stack_top - random_variable);
+	return PAGE_ALIGN(stack_top) - random_variable;
 #endif
 }
 
diff --git a/trunk/include/asm-x86_64/elf.h b/trunk/include/asm-x86_64/elf.h
index 43862cd6a569..c98633af07d2 100644
--- a/trunk/include/asm-x86_64/elf.h
+++ b/trunk/include/asm-x86_64/elf.h
@@ -8,6 +8,7 @@
 #include <asm/ptrace.h>
 #include <asm/user.h>
 #include <asm/processor.h>
+#include <asm/compat.h>
 
 /* x86-64 relocation types */
 #define R_X86_64_NONE		0	/* No reloc */
@@ -157,6 +158,9 @@ extern int dump_task_fpu (struct task_struct *, elf_fpregset_t *);
 #define ELF_CORE_COPY_TASK_REGS(tsk, elf_regs) dump_task_regs(tsk, elf_regs)
 #define ELF_CORE_COPY_FPREGS(tsk, elf_fpregs) dump_task_fpu(tsk, elf_fpregs)
 
+/* 1GB for 64bit, 8MB for 32bit */
+#define STACK_RND_MASK (is_compat_task() ? 0x7ff : 0x3fffff)
+
 #endif
 
 #endif