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authorRadu Caragea <sinaelgl@gmail.com>2013-08-13 16:00:59 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-20 08:43:02 -0700
commitf6c19e2f7d9204bca6576f03a117bec4eaaa9b5b (patch)
treea91b97087847cd76f1ae7906ca0f4430a13177d4
parent4f01c72ef36d3305d6273fe7f1f6670c52745c3d (diff)
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x86 get_unmapped_area(): use proper mmap base for bottom-up direction
commit df54d6fa54275ce59660453e29d1228c2b45a826 upstream. When the stack is set to unlimited, the bottomup direction is used for mmap-ings but the mmap_base is not used and thus effectively renders ASLR for mmapings along with PIE useless. Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Michel Lespinasse <walken@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Adrian Sendroiu <molecula2788@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kernel/sys_x86_64.c2
-rw-r--r--arch/x86/mm/mmap.c2
-rw-r--r--include/linux/sched.h1
3 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index dbded5aedb8..48f8375e4c6 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 = mmap_legacy_base();
*end = TASK_SIZE;
}
}
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 845df6835f9..c1af32385ab 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -98,7 +98,7 @@ static unsigned long mmap_base(void)
* Bottom-up (legacy) layout on X86_32 did not support randomization, X86_64
* does, but not when emulating X86_32
*/
-static unsigned long mmap_legacy_base(void)
+unsigned long mmap_legacy_base(void)
{
if (mmap_is_ia32())
return TASK_UNMAPPED_BASE;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 178a8d909f1..3aeb14b0624 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -314,6 +314,7 @@ struct nsproxy;
struct user_namespace;
#ifdef CONFIG_MMU
+extern unsigned long mmap_legacy_base(void);
extern void arch_pick_mmap_layout(struct mm_struct *mm);
extern unsigned long
arch_get_unmapped_area(struct file *, unsigned long, unsigned long,