[Devel,RHEL7,COMMIT] ms/x86: Fix norandmaps/ADDR_NO_RANDOMIZE

Submitted by Konstantin Khorenko on Sept. 1, 2017, 7:59 a.m.


Message ID 201709010759.v817xP4X007694@finist_ce7.work
State New
Series "ms/x86: Fix norandmaps/ADDR_NO_RANDOMIZE"
Headers show

Commit Message

Konstantin Khorenko Sept. 1, 2017, 7:59 a.m.
The commit is pushed to "branch-rh7-3.10.0-693.1.1.vz7.37.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.1.1.vz7.37.2
commit e11ef19abac817dfce2d7fd1609d9a782e0208f5
Author: Oleg Nesterov <oleg@redhat.com>
Date:   Tue Aug 15 17:39:52 2017 +0200

    ms/x86: Fix norandmaps/ADDR_NO_RANDOMIZE
    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: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()")
    Signed-off-by: Oleg Nesterov <oleg@redhat.com>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
    Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com>
    Cc: stable@vger.kernel.org
    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.com
    (cherry picked from commit 47ac5484fd961420e5ec0bb5b972fde381f57365)
    Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
 arch/x86/mm/mmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

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diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index a1656c8..22026df 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -81,14 +81,14 @@  static int mmap_is_legacy(void)
 static unsigned long arch_rnd(unsigned int rndbits)
+	if (!(current->flags & PF_RANDOMIZE))
+		return 0;
 	return ((unsigned long)get_random_int() &
 			((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);