On Thu, Feb 4, 2016 at 2:06 PM, Daniel Cashman <[email protected]> wrote: > 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(-)
Thanks for fixing this! Acked-by: Kees Cook <[email protected]> -Kees -- Kees Cook Chrome OS & Brillo Security
