From 47ac5484fd961420e5ec0bb5b972fde381f57365 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 15 Aug 2017 17:39:52 +0200 Subject: 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 Signed-off-by: Thomas Gleixner Acked-by: Kirill A. Shutemov Acked-by: Cyrill Gorcunov Reviewed-by: Dmitry Safonov Cc: stable@vger.kernel.org Cc: Andy Lutomirski Cc: Andrew Morton Cc: Borislav Petkov Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20170815153952.GA1076@redhat.com --- arch/x86/mm/mmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86/mm/mmap.c') 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); } -- cgit v1.1 From 01578e36163cdd0e4fd61d9976de15f13364e26d Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 15 Aug 2017 17:40:11 +0200 Subject: x86/elf: Remove the unnecessary ADDR_NO_RANDOMIZE checks The ADDR_NO_RANDOMIZE checks in stack_maxrandom_size() and randomize_stack_top() are not required. PF_RANDOMIZE is set by load_elf_binary() only if ADDR_NO_RANDOMIZE is not set, no need to re-check after that. Signed-off-by: Oleg Nesterov Signed-off-by: Thomas Gleixner Reviewed-by: Dmitry Safonov Cc: stable@vger.kernel.org Cc: Andy Lutomirski Cc: Andrew Morton Cc: Borislav Petkov Cc: Linus Torvalds Cc: "Kirill A. Shutemov" Link: http://lkml.kernel.org/r/20170815154011.GB1076@redhat.com --- arch/x86/mm/mmap.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'arch/x86/mm/mmap.c') diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index c94df12..a88cfbf 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -50,8 +50,7 @@ unsigned long tasksize_64bit(void) static unsigned long stack_maxrandom_size(unsigned long task_size) { unsigned long max = 0; - if ((current->flags & PF_RANDOMIZE) && - !(current->personality & ADDR_NO_RANDOMIZE)) { + if (current->flags & PF_RANDOMIZE) { max = (-1UL) & __STACK_RND_MASK(task_size == tasksize_32bit()); max <<= PAGE_SHIFT; } -- cgit v1.1