FROMLIST: mm: mmap: Add new /proc tunable for mmap_base ASLR.

(cherry picked from commit

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.

Signed-off-by: Daniel Cashman <>
Signed-off-by: Daniel Cashman <>

Bug: 27796957
Patchset: ASLR sysctl

Change-Id: Iaf2c4ca27146a7d9ed03f34aefab82cd0735368e
Signed-off-by: Kees Cook <>
5 files changed