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Subject[PATCH 0/2] Fix mmap_base entropy for >31 bits.
Date
Upstream commit: d07e22597d1d355829b7b18ac19afa912cf758d1 added the
ability to choose from a range of values to use for entropy count in
generating the random offset to the mmap_base address. The
maximum value on this range was set to 32 bits for 64-bit x86 systems,
but this value could be increased further, requiring more than the 32
bits of randomness provided by get_random_int(), as is already possible
for arm64. Add a new function: get_random_long() which more naturally
fits with the mmap usage of get_random_int() but operates exactly the
same as get_random_int().

Also, fix the shifting constant in mmap_rnd() to be an unsigned long so
that values greater than 31 bits generate an appropriate mask without
overflow. This is especially important on x86, as its shift instruction
uses a 5-bit mask for the shift operand, which meant that any value for
mmap_rnd_bits over 31 acts as a no-op and effectively disables mmap_base
randomization.

Finally, replace calls to get_random_int() with get_random_long() where
appropriate.

Daniel Cashman (2):
drivers: char: random: Add get_random_long().
use get_random_long().

arch/arm/mm/mmap.c | 2 +-
arch/arm64/mm/mmap.c | 4 ++--
arch/mips/mm/mmap.c | 4 ++--
arch/powerpc/kernel/process.c | 4 ++--
arch/powerpc/mm/mmap.c | 4 ++--
arch/sparc/kernel/sys_sparc_64.c | 2 +-
arch/x86/mm/mmap.c | 6 +++---
drivers/char/random.c | 22 ++++++++++++++++++++++
fs/binfmt_elf.c | 2 +-
include/linux/random.h | 1 +
10 files changed, 37 insertions(+), 14 deletions(-)

--
2.7.0.rc3.207.g0ac5344

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