Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.12 30/41] x86: Fix norandmaps/ADDR_NO_RANDOMIZE | Date | Tue, 22 Aug 2017 12:13:58 -0700 |
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4.12-stable review patch. If anyone has any objections, please let me know.
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From: Oleg Nesterov <oleg@redhat.com>
commit 47ac5484fd961420e5ec0bb5b972fde381f57365 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: 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: 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 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/x86/mm/mmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -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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