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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 /Documentation | |
| parent | b37549b9638e3d702eb6cd28e83767cccb4d164a (diff) | |
| download | kernel_samsung_tuna-56ec74e215e7eed1634e82cdc2bec5e28422808a.zip kernel_samsung_tuna-56ec74e215e7eed1634e82cdc2bec5e28422808a.tar.gz kernel_samsung_tuna-56ec74e215e7eed1634e82cdc2bec5e28422808a.tar.bz2 | |
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 'Documentation')
| -rw-r--r-- | Documentation/sysctl/vm.txt | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 9c11d97..912dc72 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -41,6 +41,8 @@ Currently, these files are in /proc/sys/vm: - min_slab_ratio - min_unmapped_ratio - mmap_min_addr +- mmap_rnd_bits +- mmap_rnd_compat_bits - nr_hugepages - nr_overcommit_hugepages - nr_pdflush_threads @@ -425,6 +427,33 @@ against future potential kernel bugs. ============================================================== +mmap_rnd_bits: + +This value can be used to select the number of bits to use to +determine the random offset to the base address of vma regions +resulting from mmap allocations on architectures which support +tuning address space randomization. This value will be bounded +by the architecture's minimum and maximum supported values. + +This value can be changed after boot using the +/proc/sys/vm/mmap_rnd_bits tunable + +============================================================== + +mmap_rnd_compat_bits: + +This value can be used to select the number of bits to use to +determine the random offset to the base address of vma regions +resulting from mmap allocations for applications run in +compatibility mode on architectures which support tuning address +space randomization. This value will be bounded by the +architecture's minimum and maximum supported values. + +This value can be changed after boot using the +/proc/sys/vm/mmap_rnd_compat_bits tunable + +============================================================== + nr_hugepages Change the minimum size of the hugepage pool. |