[ 3.8.y.z extended stable ] Patch "x86 get_unmapped_area: Access mmap_legacy_base through mm_struct" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    x86 get_unmapped_area: Access mmap_legacy_base through mm_struct

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.8.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From d737b193cce63a404afa54829e4553b422285086 Mon Sep 17 00:00:00 2001
From: Radu Caragea <sinaelgl at gmail.com>
Date: Wed, 21 Aug 2013 20:55:59 +0300
Subject: x86 get_unmapped_area: Access mmap_legacy_base through mm_struct
 member

commit 41aacc1eea645c99edbe8fbcf78a97dc9b862adc upstream.

This is the updated version of df54d6fa5427 ("x86 get_unmapped_area():
use proper mmap base for bottom-up direction") that only randomizes the
mmap base address once.

Signed-off-by: Radu Caragea <sinaelgl at gmail.com>
Reported-and-tested-by: Jeff Shorey <shoreyjeff at gmail.com>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Michel Lespinasse <walken at google.com>
Cc: Oleg Nesterov <oleg at redhat.com>
Cc: Rik van Riel <riel at redhat.com>
Cc: Ingo Molnar <mingo at elte.hu>
Cc: Adrian Sendroiu <molecula2788 at gmail.com>
Cc: Greg KH <greg at kroah.com>
Cc: Kamal Mostafa <kamal at canonical.com>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/x86/kernel/sys_x86_64.c | 2 +-
 arch/x86/mm/mmap.c           | 6 ++++--
 include/linux/mm_types.h     | 1 +
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 97ef74b..9e9a72c 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -101,7 +101,7 @@ static void find_start_end(unsigned long flags, unsigned long *begin,
 				*begin = new_begin;
 		}
 	} else {
-		*begin = TASK_UNMAPPED_BASE;
+		*begin = current->mm->mmap_legacy_base;
 		*end = TASK_SIZE;
 	}
 }
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 845df68..5c1ae28 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -112,12 +112,14 @@ static unsigned long mmap_legacy_base(void)
  */
 void arch_pick_mmap_layout(struct mm_struct *mm)
 {
+	mm->mmap_legacy_base = mmap_legacy_base();
+	mm->mmap_base = mmap_base();
+
 	if (mmap_is_legacy()) {
-		mm->mmap_base = mmap_legacy_base();
+		mm->mmap_base = mm->mmap_legacy_base;
 		mm->get_unmapped_area = arch_get_unmapped_area;
 		mm->unmap_area = arch_unmap_area;
 	} else {
-		mm->mmap_base = mmap_base();
 		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
 		mm->unmap_area = arch_unmap_area_topdown;
 	}
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index f8f5162..7716e38 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -332,6 +332,7 @@ struct mm_struct {
 	void (*unmap_area) (struct mm_struct *mm, unsigned long addr);
 #endif
 	unsigned long mmap_base;		/* base of mmap area */
+	unsigned long mmap_legacy_base;         /* base of mmap area in bottom-up allocations */
 	unsigned long task_size;		/* size of task vm space */
 	unsigned long cached_hole_size; 	/* if non-zero, the largest hole below free_area_cache */
 	unsigned long free_area_cache;		/* first hole of size cached_hole_size or larger */
--
1.8.1.2