Commit 932769e1 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Greg Kroah-Hartman

x86: Fix norandmaps/ADDR_NO_RANDOMIZE

commit 47ac5484 upstream.

Documentation/admin-guide/kernel-parameters.txt says:

    norandmaps  Don't use address space randomization. Equivalent
                to echo 0 > /proc/sys/kernel/randomize_va_space

but it doesn't work because arch_rnd() which is used to randomize
mm->mmap_base returns a random value unconditionally. And as Kirill
pointed out, ADDR_NO_RANDOMIZE is broken by the same reason.

Just shift the PF_RANDOMIZE check from arch_mmap_rnd() to arch_rnd().

Fixes: 1b028f78 ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()")
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
Reviewed-by: default avatarDmitry Safonov <dsafonov@virtuozzo.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20170815153952.GA1076@redhat.comSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c588e0cb
......@@ -82,13 +82,13 @@ static int mmap_is_legacy(void)
static unsigned long arch_rnd(unsigned int rndbits)
{
if (!(current->flags & PF_RANDOMIZE))
return 0;
return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
}
unsigned long arch_mmap_rnd(void)
{
if (!(current->flags & PF_RANDOMIZE))
return 0;
return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
}
......
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