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authorOleg Nesterov <oleg@redhat.com>2017-08-15 17:39:52 +0200
committerThomas Gleixner <tglx@linutronix.de>2017-08-16 20:32:01 +0200
commit47ac5484fd961420e5ec0bb5b972fde381f57365 (patch)
treec18c896db669c488159a0ad412dc999931127346 /arch
parent84393817db09bb436e934f8f8cc981cbca9ea4dc (diff)
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
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/mm/mmap.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 229d04a83f85..c94df122815a 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);
}