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| author | dcashman <dcashman@google.com> | 2015-12-29 14:24:39 -0800 |
|---|---|---|
| committer | Ziyan <jaraidaniel@gmail.com> | 2016-10-29 01:33:53 +0200 |
| commit | 56ec74e215e7eed1634e82cdc2bec5e28422808a (patch) | |
| tree | 7e88d04f15a37216bc7fc7ecc628d31acf29e6fe /mm | |
| parent | b37549b9638e3d702eb6cd28e83767cccb4d164a (diff) | |
| download | kernel_samsung_tuna-56ec74e215e7eed1634e82cdc2bec5e28422808a.tar.gz kernel_samsung_tuna-56ec74e215e7eed1634e82cdc2bec5e28422808a.tar.bz2 kernel_samsung_tuna-56ec74e215e7eed1634e82cdc2bec5e28422808a.zip | |
FROMLIST: mm: mmap: Add new /proc tunable for mmap_base ASLR.
(cherry picked from commit https://lkml.org/lkml/2015/12/21/337)
ASLR only uses as few as 8 bits to generate the random offset for the
mmap base address on 32 bit architectures. This value was chosen to
prevent a poorly chosen value from dividing the address space in such
a way as to prevent large allocations. This may not be an issue on all
platforms. Allow the specification of a minimum number of bits so that
platforms desiring greater ASLR protection may determine where to place
the trade-off.
Bug: 24047224
Signed-off-by: Daniel Cashman <dcashman@android.com>
Signed-off-by: Daniel Cashman <dcashman@google.com>
Change-Id: Ic74424e07710cd9ccb4a02871a829d14ef0cc4bc
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/mmap.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 96f124e15a8..05ee0a467ea 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -46,6 +46,18 @@ #define arch_rebalance_pgtables(addr, len) (addr) #endif +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS +const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN; +const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX; +int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS; +#endif +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS +const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN; +const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX; +int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS; +#endif + + static void unmap_region(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *prev, unsigned long start, unsigned long end); |