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Commit df54d6fa authored by Radu Caragea's avatar Radu Caragea Committed by Linus Torvalds
Browse files

x86 get_unmapped_area(): use proper mmap base for bottom-up direction 



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.

Cc: Michel Lespinasse <walken@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Adrian Sendroiu <molecula2788@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c7dd3392

arch/x86/kernel/sys_x86_64.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

	}

}

arch/x86/mm/mmap.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -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,