Messages in this thread Patch in this message |  | | Date | Tue, 15 Aug 2017 17:39:52 +0200 | From | Oleg Nesterov <> | Subject | [PATCH v2 1/2] x86: fix norandmaps/ADDR_NO_RANDOMIZE |
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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().
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Cyrill Gorcunov <gorcunov@openvz.org> Fixes: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()") Cc: stable <stable@vger.kernel.org> [4.12+] --- arch/x86/mm/mmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index 229d04a..c94df12 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -79,13 +79,13 @@ 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); } -- 2.5.0
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