Re: [PATCH v3 10/11] mips: Use generic mmap top-down layout

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 4/18/19 1:31 AM, Kees Cook wrote:
On Wed, Apr 17, 2019 at 12:33 AM Alexandre Ghiti <alex@xxxxxxxx> wrote:
mips uses a top-down layout by default that fits the generic functions.
At the same time, this commit allows to fix problem uncovered
and not fixed for mips here:
https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1429066.html

Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>

Thanks !



-Kees

---
  arch/mips/Kconfig                 |  1 +
  arch/mips/include/asm/processor.h |  5 ---
  arch/mips/mm/mmap.c               | 67 -------------------------------
  3 files changed, 1 insertion(+), 72 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 4a5f5b0ee9a9..ec2f07561e4d 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -14,6 +14,7 @@ config MIPS
         select ARCH_USE_CMPXCHG_LOCKREF if 64BIT
         select ARCH_USE_QUEUED_RWLOCKS
         select ARCH_USE_QUEUED_SPINLOCKS
+       select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
         select ARCH_WANT_IPC_PARSE_VERSION
         select BUILDTIME_EXTABLE_SORT
         select CLONE_BACKWARDS
diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h
index aca909bd7841..fba18d4a9190 100644
--- a/arch/mips/include/asm/processor.h
+++ b/arch/mips/include/asm/processor.h
@@ -29,11 +29,6 @@

  extern unsigned int vced_count, vcei_count;

-/*
- * MIPS does have an arch_pick_mmap_layout()
- */
-#define HAVE_ARCH_PICK_MMAP_LAYOUT 1
-
  #ifdef CONFIG_32BIT
  #ifdef CONFIG_KVM_GUEST
  /* User space process size is limited to 1GB in KVM Guest Mode */
diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
index ffbe69f3a7d9..61e65a69bb09 100644
--- a/arch/mips/mm/mmap.c
+++ b/arch/mips/mm/mmap.c
@@ -20,43 +20,6 @@
  unsigned long shm_align_mask = PAGE_SIZE - 1;  /* Sane caches */
  EXPORT_SYMBOL(shm_align_mask);

-/* gap between mmap and stack */
-#define MIN_GAP                (128*1024*1024UL)
-#define MAX_GAP                ((STACK_TOP)/6*5)
-#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))
-
-static int mmap_is_legacy(struct rlimit *rlim_stack)
-{
-       if (current->personality & ADDR_COMPAT_LAYOUT)
-               return 1;
-
-       if (rlim_stack->rlim_cur == RLIM_INFINITY)
-               return 1;
-
-       return sysctl_legacy_va_layout;
-}
-
-static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
-{
-       unsigned long gap = rlim_stack->rlim_cur;
-       unsigned long pad = stack_guard_gap;
-
-       /* Account for stack randomization if necessary */
-       if (current->flags & PF_RANDOMIZE)
-               pad += (STACK_RND_MASK << PAGE_SHIFT);
-
-       /* Values close to RLIM_INFINITY can overflow. */
-       if (gap + pad > gap)
-               gap += pad;
-
-       if (gap < MIN_GAP)
-               gap = MIN_GAP;
-       else if (gap > MAX_GAP)
-               gap = MAX_GAP;
-
-       return PAGE_ALIGN(STACK_TOP - gap - rnd);
-}
-
  #define COLOUR_ALIGN(addr, pgoff)                              \
         ((((addr) + shm_align_mask) & ~shm_align_mask) +        \
          (((pgoff) << PAGE_SHIFT) & shm_align_mask))
@@ -154,36 +117,6 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp,
                         addr0, len, pgoff, flags, DOWN);
  }

-unsigned long arch_mmap_rnd(void)
-{
-       unsigned long rnd;
-
-#ifdef CONFIG_COMPAT
-       if (TASK_IS_32BIT_ADDR)
-               rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
-       else
-#endif /* CONFIG_COMPAT */
-               rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
-
-       return rnd << PAGE_SHIFT;
-}
-
-void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
-{
-       unsigned long random_factor = 0UL;
-
-       if (current->flags & PF_RANDOMIZE)
-               random_factor = arch_mmap_rnd();
-
-       if (mmap_is_legacy(rlim_stack)) {
-               mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
-               mm->get_unmapped_area = arch_get_unmapped_area;
-       } else {
-               mm->mmap_base = mmap_base(random_factor, rlim_stack);
-               mm->get_unmapped_area = arch_get_unmapped_area_topdown;
-       }
-}
-
  static inline unsigned long brk_rnd(void)
  {
         unsigned long rnd = get_random_long();
--
2.20.1





[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux